Space Warfare Strategy and Tactics

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  From Star Trek: Wrath of Khan (1982)

KIRK: Spock?

SPOCK: Sporadic energy readings port side, aft. Could be an impulse turn.

KIRK: He won't break off now. He followed me this far, he'll be back. But, from where...?

SPOCK: He's intelligent, but not experienced. His pattern indicates two-dimensional thinking...

Kirk looks at him, smiles.

KIRK: Full stop.

SULU: Full stop, sir.

KIRK: Descent ten thousand meters. Stand by photon torpedoes.

Starship Enterprise moves downward ten thousand meters. Khan's ship sails by overhead blissfully unaware. Enterprise rises up behind Khan's ship like a striking cobra and shoots Khan's derrière off.

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6. When attacking a StarGate, converge on it from different three-dimensional directions as much as possible, again to avoid the StarGate's combat cast.

8. Never lose sight of the immensity of the volume represented by the Stellar Display. It is almost impossible to be caught in mid-space, and if you are careful, your opponent will never discover the strength of a given force until you want him to.

10. Establishing "picket lines" or "screens" of units in space never works. It is a waste of available force and is easily countered by the Enemy. The environment is a vast three-dimensional sea - not a small, flat lake.

"Did you know, Henlo, that certain eminent military tacticians have proved to my satisfaction that war in space is impossible?"

Henlo arched the fur over his eyes. "I haven't hear the theory."

"No, I didn't think you had," Miranid said in a rambling town of voice. "However, our present situation is a splendid example."

"Consider. If you picture the present Vilkan holdings (empire) as a solid sphere in space, bristling with weapons pointed outward, and our own fleet as a hollow sphere designed to contain and crush it, then you must allow that all Farla with half the Galaxy to help it could not supply us with enough strength to keep our sphere impenetrable from the inside at all points. With further problems of uncertain ship detection in hyperspace we could not prevent repeated breakthroughs from the inside."

"Once our hollow sphere is broken it is caught between two fires, and gradually decimated if it does not withdraw into a larger, and even more porous, sphere -- which can again be broken. Thus, stalemate, eventual disgust, and finally an inconclusive peace at an inconclusive price."

"Now, since we are not going to be foolish enough to form such a sphere the only alternative is to attempt an attack by a knife-like method. We can spit, split, slice, or whittle."

"Spitting is out of the question. If we try to drive through, we expose ourselves to attack from all sides. The splitting process gives rise to the same objections. This leaves slicing or whittling -- and since a whittle is only a small slice, or a slice a large whittle, let us discuss them simultaneously."

Miranid looked steadily at Henlo.

"I will not whittle if I can slice, but I cannot slice, and for the same reason, I cannot whittle. For this is not a clay sphere, Henlo, but a steel ball -- and red-hot, to boot. With every stroke I make, I will lose a greater percentage of my available ships than the enemy will."

"His supply lines are short -- I've shortened them for him. His ships can land, be repaired, refueled, and re-armed, their crews replaced by fresh men, and sent back into battle a hundred times for each new ship that can reach me from Farla. I have a limited supply of men, equipment, and food. With every stroke, I wear down my sharpness a little more."

He paused an instant, then went on, "Until, finally, I attack the sphere for one last time and my dull, worn knife slips off the surface without leaving an impression. So again, stalemate, eventual disgust, and no true peace -- that is, no peace which will not leave conditions immediately ripe for another useless war."

"I would say, as a matter of fact, that this same theory makes true peace impossible so long as any wars are attempted."

(Then Miranid explains how he is going to avoid this unhappy state of affairs in the special case before them.)

...There are two great factors in space warfare that will set it off sharply from anything else in human experience, and those two factors will modify fighting ship types, strategy and tactics profoundly. They are: (a) the extent of space. and (b) the tremendous speed of the vessels...

...Speeds in space are as stupendous as the spaces they traverse. Needing seven miles per second to escape the Earth and another twenty to make any reasonable progress between the planets, even the slowest vessels will have speeds of twenty-five miles per second. Warships, presumably, according to type, will have correspondingly higher speeds—perhaps as high as fifty miles per second for the faster scouts...

...When we talk of gunfire or any other means of offense, we have to hear these dizzy speeds firmly in mind. The conclusion is irresistible that scouting, tracking, range finding and relative bearings will all be observed otherwise than visually...

...Each of the combatants must compute the other's course from blind bearings and ranges and lay their guns or point their torpedo tubes by means of a differential calculator.

However, in this blind tracking there is one peculiarity of these ships that while it is in one sense a source of danger to them, is of distinct assistance. In the fleeting minutes of their contact, neither can appreciably alter course or speed! This is a point that writers of fiction frequently ignore for the sake of vivid action, but nevertheless it is an unavoidable characteristic of the ether-borne ship.

The human body can withstand only so much acceleration and the momentum these vessels carry has been built up, hour after hour, by piling increment of speed on top of what had been attained before. In space there is no resistance. Once the rockets are cut, the ship will soar on forever at what ever velocity she had at the moment of cutting. Her master may flip her end over end and reverse his acceleration, but his slowing will be as tedious and cautious as his working up to speed. Jets flung out at right angles merely add another slight component to the velocity, checking nothing.

Rocket experts have stated that an acceleration of one hundred feet per second per second can be withstood by a human being—perhaps one hundred and fifty in an emergency. The master of a vessel proceeding at forty miles per second applying such an acceleration at right angles would succeed in deflecting his flight about one hundred miles by the end of the first minute, during which he will have run twenty-four hundred—a negligible turn, if under fire. Applied as a direct brake, that hundred miles of decreased velocity would slow him by one twenty-fourth—obviously not worth the doing if the emergency is imminent.

WITH these conditions in mind, let us imagine a light cruiser of the future bowling along at forty miles per second on the trail of an enemy. The enemy is also a cruiser, one that has slipped through our screen and is approaching the earth for a fast raid on our cities. He is already decelerating for his prospective descent and is thought to be about one hundred and fifty thousand miles ahead, proceeding at about thirty-five miles per second. Our cruiser is closing on him from a little on his port quarter, and trying to pick him up with its direction finders.

So far we have not seen him. We only know from enciphered code messages received several days ago from our scouting force, now fifty millions astern of us, that he is up ahead. It would take too long here to explain how the scouts secured the information they sent us. The huge system of expanding spirals along which successive patrols searched the half billion cubic miles of dangerous space lying between us and the enemy planet is much too intricate for brief description. It is sufficient for our purposes that the scouts did detect the passage of the hostile cruiser through their web and that they kept their instruments trained on him long enough to identify his trajectory. Being neither in a position to attack advantageously nor well enough armed—for their function is the securing of information, and that only—they passed the enemy's coordinates along to us. This information is vital to us, for without it the probability of contact in the void is so remote as to he nonexistent.

The ship in which we are rushing to battle is not a large one. She is a bare hundred meters in length, but highly powered. Her multiple rocket tubes, now cold and dead, are grouped in the stern. We have no desire for more speed, having all that is manageable already, for after the few seconds of our coming brush with the enemy our velocity is such that we will far overrun him and his destination as well, it will require days of maximum deceleration for us to check our flight and be in a position to return to base.

Our ship's armament, judged by today's standards, will at first sight appear strangely inadequate. Our most destructive weapon is the mine, a simple sphere of meteoric iron about the size of a billiard ball, containing no explosive and not fused. The effectiveness of such mines depends upon the speed with which they are struck by the target ship—no explosive could add much to the damage done by a small lump if iron striking at upward of thirty miles a second. Then there will be torpedo tubes amidships. and perhaps a few guns. but it may be well to post pone a discussion of the armament until we have examined the conditions at the place of battle.

Although we know in a general way where the enemy is and where he is going, before we close with him we must determine his course and speed very accurately, for our ability to hit him at all is going to depend upon extremely nice calculations. Our speeds are such that angular errors of so much as a second of arc will be fatal, and times must be computed to within hundredths of seconds.

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  Figure 1

This falls within the province of fire-control, a subject seldom if ever mentioned by fiction writers. There is no blame to be attached to them for that, for the problems of fire-control are essentially those of pure mathematics, and mathematics is notoriously unthrilling to the majority of readers. Yet hitting with guns—or even arrows, though the archer solves his difficulties by intuition—requires the solution of intricate problems involving the future positions and movements of at least two bodies, and nothing more elementary than the differential calculus will do the trick. In these problems interior ballistics, for all its interesting physics, boils down to a single figure—the initial velocity of the projectile, while exterior ballistics evaporates for the most part the moment we propel our missile into a gravityless vacuum. In space we are to be concerned with the swiftly changing relationship of two rapidly moving vessels and the interchange of equally swift projectiles between them, the tracks of all of them being complicated curves and not necessarily lying in a plane.

In its simplest statement the problem of long-range gunnery is this: where will the enemy be when my salvo gets there? For we must remember that even in today's battles the time the projectile spends en-route to its target is appreciable—fully a minute on occasion, at sea, during which the warship fired upon may move as much as half a mile. Under such circumstances the gunner does not fire directly at his target, but at the place it is going to be. That requires very accurate knowledge of where the enemy is headed and how fast he is moving.

At sea that is done by observing successive bearings and ranges and plotting them as polar co-ordinates, bearing in mind that the origin is continuously shifting due to the ship's own motion. This work of tracking—the subsequent range-keeping and prediction of future ranges and bearings—is done in our times in the plotting room. This is the most vital spot in the ship, for if her weapons may be likened to fists and her motive power to legs, her optical and acoustical instruments to eyes and ears. then the plotting room is the counterpart of the brain. There all the information is received, corrected, digested, and distributed throughout the ship. Without that co-ordination and direction the ship would be as helpless as an idiot.

Well, hardly that helpless today. Our individual units, such as turret crews, can struggle on alone, after a fashion. But not so with the ship of the future. There the plotting room is everything, and when it is put out of commission, the ship is blind and paralyzed. It will, of course, be located within the center of the ship, surrounded by an armored shell of its own, and in there will also be the ship control stations.

THE BEST WAY to approach the problems our descendants will have to face is to consider a simple problem in tracking that our own warships deal with daily. It is an absurdly simple one compared to the warped spirals to be handled in space warfare, but it will serve to illustrate the principle. In Fig. 1. it is shown graphically, but in actual practice the elements of the problem are set up on a motor-driven machine which thereupon continuously and correctly delivers the solutions of problems that would take an Einstein minutes to state. As the situation outside changes, corrections are cranked into the machine, which instantly and uncomplainingly alters its calculations.

In the figure we have the tracks of two ships, ours the left-hand one. For the sake of clarity and emphasis I have made the ratio of speeds three to one, hut the same trends would be shown at the more usual ratio of, say, 20:19.

At positions 1, 2, 3 and so on, we observe the range and bearing of the target, and plot them. By noting the differences between successive readings and the second differences between those, we soon have an idea of the type of curve the rates of changes would plot into. In a short time we can also note that the rates themselves are changing at a certain rate. This is a rough sort of differentiation—by inspection—and to one familiar with such curves these trends have a definite meaning.

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For example, it is apparent that the series of observed angles Beta; are steadily opening, signifying that we are drawing past the target. Any sudden alteration of the second differences, such as occurs at 8, at once indicates a change of condition on the part of the enemy. He has either turned sharply away or slowed to half speed, for the bearing suddenly opens nearly two degrees more than the predicted bearing. We learn which by consulting our ranges. It could be a combination of changed course and changed speed.

The ranges during the first seven time-intervals have been steadily decreasing, although the rate of decrease has been slowing up, indicating we are approaching the minimum range. At 8, though, the range not only fails to decrease, but the rate of change actually changes sign. We know without doubt that the enemy has turned away.

The importance of having the machine grind out predicted bearings and ranges, aside from the desirability of speed and accuracy, is that at any moment smoke, a rain squall, or intervening ships may obscure the target. In that event the gunners need never know the difference—their range and bearing indicators are ticking away like taximeters, fed figures by the controlling range-keeper. It would not have mattered if sight had been lost of the enemy at 4; the gun fire would have been just as accurate up to the time he changed course as if they had the target in plain sight.

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  Figure 1 (a)

As a matter of fact, the guns are not pointed at the target at all, but in advance of it, as is shown in Fig. 1 (a), both range and bearing being altered to allow for the forward movements of the target while the shells are in the air. The projectiles may be regarded as moving objects launched on a collision course with regard to the enemy vessel.

Speaking of collision courses, it is an interesting property of relative bearings that when the bearing remains constant—except in the special case of the vessels being on parallel courses at identical speeds—the vessels will eventually collide, regardless of what their actual courses and speeds are. Hence, from the time the shots of the salvo left their guns until they struck their target, the target bore a constant angle of thirteen degrees to the right of the nose of the shells. (This knowledge has some utility in estimating the penetration of armor at the destination.)

In the example above, all the movement can be regarded as taking place in a plane; the ships follow straight courses and they maintain constant speeds. Our terrestrial problems are in practice much complicated by zigzagging, slowing down and speeding up, but at that they are relatively child's play compared to what the sky-warrior of the future must contend with.

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His tracks are likely to he curved in three dimensions, like pieces of wire hacked out of a spiral bedspring, and whether or not they can be plotted in a plane, they will nowhere be straight. Moreover, whatever changes of speeds occur will be in the form of steady accelerations and not in a succession of flat steps linked by brief accelerations such as we know. Computing collision courses between two continually accelerating bodies is a much trickier piece of mathematical legerdemain than finding the unknown quantities in the family of plane trapeziums shown in Fig. 1. Yet projectiles must be given the course and speed necessary to insure collision.

The gunnery officer of the future is further handicapped by rarely ever being permitted a glimpse of his target, certainly not for the purpose of taking ranges and bearings. In the beginning of the approach the distances between the ships is much too great, and by the time they have closed, their relative speed will generally forbid vision.

SINCE optical instruments are useless except for astragational purposes, his range-finders and target-bearing transmitters will have to be something else. For bearings, his most accurate instrument will probably be the thermoscope—an improved heat-detector similar to those used by astronomers in comparing the heat emission of distant stars. It will have a spherical mounting with a delicate micro-vernier. A nearby space ship is sure to radiate heat, for it is exposed constantly to full sunlight and must rid itself of the excess heat or its crew will die. Once such a source of heat is picked up and identified, it can be followed very closely as to direction, although little can be told of its distance unless something is known of its intrinsic heat radiation.

Ranges will probably be determined by sounding space with radio waves, measuring the time interval to the return of reflected waves. It is doubtful whether this means will have a high degree of accuracy much beyond ranges of one light-second on account of the movement of the two vessels while the wave is in transit both ways. At long ranges the need for troublesome corrections is sure to enter.

Such observations, used in conjunction with one another, should give fairly accurate information as to the target's trajectory and how he bears from us and how far he is away. This data will be fed into a tracking and range-keeping machine capable of handling the twisted three-dimensional curves involved, and which will at once indicate the time and distance of the closest point of approach. Both captains will at once begin planning the action. They may also attempt to adjust their courses slightly, but since the rockets evolve great heat, neither can hope to keep his action from the knowledge of the other owing to the sensitiveness of the thermoscopes.

Assuming we have, by observation and plotting, full knowledge of the enemy's path and have come almost into position to commence the engagement, we find ourselves confronted once more with the two overwhelming factors of space warfare—great distance and immense speeds—but this time in another aspect. We have come up close to our foe—in fact we are within twenty seconds of intersecting his trajectory—and our distance apart is a mere four hundred miles. It is when we get to close quarters that the tremendous problems raised by

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  Figure 2

Look at Fig. 2.

The elapsed time from the commencement of the engagement until the end is less than twenty seconds. Our ship is making forty miles per second, the other fellow is doing thirty-three. We will never be closer than fifty miles, even if we regard the curves as drawn as being in the same plane. If one rides over or below the other, that minimum range will be greater. What kind of projectile can cross the two or three hundred miles separating the two converging vessels in time to collide with the enemy? Shooting cannon with velocities as low as a few miles per second would be like sending a squadron of snails out from the curb to intercept an oncoming motorcycle—it would be out of sight in the distance before they were well started.

Projectiles from guns, if they were to be given velocities in the same relation to ships' speeds that prevail at present, would have to be stepped up to speeds of three to four thousand miles per second! A manifest impossibility. It would be difficult, indeed, to hurl any sort of projectile away from the ship at greater initial velocities than the ship's own speed. Such impulses, eighty times stronger than the propelling charge of today's cannon, would cause shocks of incredible violence. It follows from that that an overtaken ship is comparatively helpless—unless she is in a position to drop mines—for whatever missiles she fires have the forward inertia of the parent ship and will therefore be sluggish in their movement in any direction but ahead.

Another difficulty connected with gunfire is the slowness with which it comes into operation. This may seem to some to be a startling statement, but we are dealing here with astonishing speeds. When the firing key of a piece of modern artillery is closed, the gun promptly goes off with a bang. To us that seems to be a practically instantaneous action. Yet careful time studies show the following sequence of events: the primer fires, the powder is ignited and burns, the gases of combustion expand and start the shell moving down the tube. The elapsed time from the will to fire to the emergence of the projectile from the muzzle is about one tenth of a second. In Fig. 2 our target will have moved more than three miles while our shell is making its way to the mouth of the cannon! It looks as if guns wouldn't do.

I COME to that conclusion very reluctantly, for I am quite partial to guns as amazingly flexible and reliable weapons, hut when we consider that both powders and primers vary some what in their time of burning, there is also a variable error of serious proportions added to the above slowness. It is more likely that the rocket-torpedoes suggested by Mr. Willy Ley in a recent article on space war will be the primary weapon of the future. They have the advantage of auto-acceleration and can therefore build up speed to any desired value after having been launched.

The exact moment of their firing would have to be computed by the tracking machine, as no human brain could solve such a problem in the time allowed. But even assuming machine accuracy, great delicacy in tube-laying and micro-timing, the chances of a direct hit on the target with a single missile is virtually nil. For all their advanced instruments, it is probable that all such attacks will be made in salvos, or continuous barrages. following the time honored shotgun principle. For the sake of simplicity, only two such salvos are shown on the diagram. but probably they would be as nearly continuous as the firing mechanisms of the tubes would permit. Any reader with a flair for mathematics is invited to compute the trajectories of the torpedoes. The ones shown were fired dead abeam in order to gain distance toward the enemy as rapidly as possible...

...Spotting, as we know it, would be impossible, for the target would be invisible, Hits would have to be registered by the thermoscope, utilizing the heat generated by the impact. The gunnery officer could watch the flight of his torpedoes by their fiery wakes, and see his duds burst; that might give him an idea on which side of the enemy they passed in the event the thermoscopes registered no hits.

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If there were guns—and they might be carried for stratosphere use—they could be brought into action at about 15, firing broad on the starboard quarter. The shells, ... would lose some of their forward velocity and drift along in the wake of the ship while at the same time making some distance toward the oncoming enemy. These guns would be mounted in twin turrets, one on the roof and the other on the keel, cross-connected so that they would be trained and fired together. If the ship's center of gravity lay exactly between them, their being fired would not tend to put the ship into a spin in any direction. What little torque there might be, due to inequalities in the firing charge, would be taken care of by the ship's gyro-stabilizer, an instrument also needed on board to furnish a sphere of reference so that the master could keep track of his orientation.

If upon arriving at point 16 the enemy were still full of fight and desperate measures were called for, we could lay down mines. These hard little pellets would be shot out of mine-laying tubes clustered about the main driving jets. They would be shot out at slight angles from the fore-and-aft line, and given a velocity exactly equal to the ship's speed, so that they would hang motionless where they were dropped. Being cheap and small, they could be laid so thickly that the enemy could not fail to encounter several of them. If she had survived up to this point, the end would come here.

The end, that is, of the cruiser as a fighting unit. Riddled and torn, perhaps a shapeless mass of tangled wreckage, she would go hurtling on by, forever bound to her marauding trajectory. The first duty of our cruiser would be to broadcast warnings to the System, reporting the location of its own minefield, and giving the direction taken by the shattered derelict. Sweepers would be summoned to collect the mines with powerful electromagnets, while tugs would pursue and clear the sky of the remnants of the defeated Martian.

At a guess, though, space battles will not involve a lot of strategic manoeuvering. Both sides know where the other guy is, where the other guy wants to go, and roughly what course he has to take to get there. If one side wants to completely avoid the other and has any capability of doing so, they do, and no battle happens. Otherwise the "battle" is a pretty straightforward approach of the two forces, with both conducting small maneuvers to make sure the enemy doesn't hit them from extreme range.

At some point before firing starts, both sides launch their long-range missiles, and possibly a screen of interceptors. As the missiles and interceptors pass each other, they duke it out with energy weapons, kinetic-kill, and a few nukes and then whatever is left from each side's launch goes past toward the opposing fleet. Each fleet uses point-defense countermeasures against the enemy, tries last-minute invasions, and then takes whatever damage the missiles deal.

Repeat this for multiple volleys of missiles, until the fleets are within a few hundred thousand kilometers when they start pelting each other with energy weapons. They can fly past each other shooting, in which case likely one side or the other will be utterly destroyed, or one side can decide it is defeated and try to break off from battle as quickly as possible, preserving what it has left. This may not be feasible depending on how remaining fuel reserves compare to their velocity.

The dominant rules of space battle are:

1. You can't hide. The enemy probably knows where you are the moment you launch.
2. You can run or fight, but you will typically have to pick one of the two long before battle is joined, and then you're stuck with it.
3. There isn't much room for tactics and strategy. Pretty much everything is automated, and the what your computers calculate as the best possible attack strategy probably really is the best possible attack strategy. If battle is joined, and both sides have a good idea of what the capabilities of the other side's ships are, the result will be a lot more predictable than we are used to.
4. If the engagement moves into short range (i.e. beam weapon range), it will probably be decided in a single pass. This is because at those kinds of ranges, it is very easy to hit the enemy and very hard to avoid being hit. Both sides will keep hitting each other with deadly accuracy until one of them is no longer capable of shooting. The exception is if both sides pass each other at _extremely_ high speed, but this isn't likely to happen if the primary objective of one side is to do as much damage to the other side as possible (in which case it will decelerate, slowing relative velocity).
5. You may know where the other guy is from extreme range, but due to lightspeed delay, none of your weapons actually have a chance of hitting him until they get fairly close. The range of the weapons themselves isn't the determining factor at all, range of engagement is determined by the size and maneuverability of the enemy. Thus, your weapons are effective against large, stationary, or slow-moving targets at far, far longer ranges than they are against the average warship.
6. Anything which can't manoeuver had better be very heavily protected, or had better not let you get anywhere near it. This tends to eliminate the "happy medium" of space stations, they die if an enemy fleet gets in close. Anything that can't move, and move fast, had better have huge amounts of shielding and lots and lots of countermeasures, point-defense, and whatnot. Only fortified targets on planets, moons, or within large asteroids have a chance of surviving a close attack by an enemy space fleet. These bases will compensate for their lack of mobility with means of defense that spacecraft cannot have due to weight restrictions. They will be extremely heavily armored (probably with most of the important parts deep underground), and have large numbers of defensive batteries that can destroy spacecraft at long range simply by putting up so much fire that something is bound to be hit.
7. The most effective way to destroy planetary installations is not by using warships, but by using the warships to clear out enemy space forces so you can bombard the planet with asteroids or mass nuclear assault. Conventional invasion is effectively impossible, since the defenses will destroy your invasion force if they are still functional, and the only reliable way to take out the defenses is with mass bombardment. A successful planetary assault will not allow you to capture any installations intact except those that are deep underground, and to capture those you have to send in ground forces that were very expensive to transport across space. This means capture of installations isn't really a viable alternative, unless you get the enemy to surrender upon the threat of destruction.

There are a few variables for space combat.

The first is drive efficiency and top thrust. If top thrust is low enough, maneuver ceases to be a tactical concern.

The second is laser ranges — if laser ranges are long, even with high thrust, maneuver ceases to be a tactical concern.

If your engines can scale down to missile drives (Rick Robinson's torch missiles), maneuver stops being a tactical concern in terms of avoiding them, because the missile will have enough delta v (with strap on tanks or expendable stages) that it can run down the target.

AV:T's torch drives, while laughable from a space opera standpoint, are wildly optimistic at best. Likewise, AV:T's lasers, while about 5 orders of magnitude beyond current technologies, are perhaps conservative.

For essentially the same reason, a higher-performance ship should always be able to choose the range, at least so long as fuel holds out. With higher acceleration, he can match any maneuver the other guy makes, plus some extra vector to either close the range or open it.

Some exception when you get down to time and distance scales where pivot time matters, but even then, there's a pretty limited scope to the ability to "turn inside" a faster-accelerating but pivot-sluggish opponent.

Okedokee: basic set-up

• Balkanized Earth, ditto solar system.
• Too many Great Powers for stability.
• Delta vees in the tens of km/s, peak accelerations a few gee (Higher gees tend to mean lower delta vees, though).
• All sides have decent sensor nets and stealth is more or less impossible.
• Weapons have outstripped defenses, but so far nobody has built a beam weapon that can reach across AU. You do need to close with the enemy to fight them.
• Since it takes months to years to cross the system and since rocket flares are visible across the system, the target knows you are coming.

Am I right in thinking that this makes for an extremely lossy battlefield? Ten men go in, half a man comes out sort of thing?

For certain assumptions, yes. Obviously conventional ideas of surprise and tactical manouver are compromised in the above scenario, show up at the enemies gate and he knows where and when you are coming, along with some idea of your numbers. But fear not, human ingenuity will never fail to find ways to kill other people. A number of possible strategies come to mind to get around this problem.

But first, the big assumption of your scenario: that the war is being fought between two powers on opposite sides of the Galaxy. Given that this is a highly Balkanized set-up, this seems improbable. Most countries will be mainly concerned with their immediate area, and rocket flares won't be a concern if Manhattan is invading Brooklyn (say), and only a little more when L5A invades L5B. Those with wider concerns will probably have Allies in the region.

That being said, some useful strategies for your scenario:

1. The Ace in the Hole: They know how many rockets you have, and where they are going and (more or less) when they will get there, but do they know what's on them? A common strategy might be to pack many tactical vehicles onto one "thruster pack" which then breaks up on arrival. This obfuscates both force numbers and composition, even good visuals won't tell what the interior ships are...
2. The Trojan Horse: The big trade fleet comes from across the system and, surprise! It's not a trade fleet... It could even be a supposed ally changing his colors instead of relieving you.
3. The Stab in the Back: You send out your forces to meet the enemy a safe distance away from the colony, and before you can get them back, the guy next door (in a secret pact with the enemy) is going for your throat.
4. Multiball madness: Launch a whole bunch of drones/kamikaze fighters to overwhelm enemy defenses and hope some get through. It might be useful to combine this with the thruster pack idea and have the pack break up into no-return death balls.
5. Routine Patrol: Useful for your would-be hegemons, the great power regularly sends an overwhelming show of force out on "anti-piracy patrol" (or whatever). You know when they will arrive, you know what their force is, you know you can't beat them unless you take 'em by surprise. What you don't know is whether they come in peace and will let you fete the Admiral to show the neighbors that everything is just copacetic with the big boys, or if they come to deliver, and implement, a declaration of war.
6. The Riccochet: You don't send your force to the enemy, you send it to a nearby ally, who adds his own troops, and launches a close range combined attack.
7. Cool Running: Accelerate to a decent speed, use a low emissions method to alter your course slightly (so that it's not obvious where the ships that disappeared are going), and be prepared to wait a while to get to your target. If you can pull off the attack on a flyby (or crash), that's ideal. Otherwise, your deceleration will give things away, but hopefully too late. (ed note: I personally consider this option problematic due to the impossibility of ships "disappearing".)

Other than that, I would suggest that invasion would probably be downplayed as a means of trans-system warfare. Instead, the focus would probably be on using proxies, supporting privateers, terrorists, and other NGAs (non-governmental armies...), building isolating alliances, trade interdiction, financial interference, lightspeed infostructure and psyops attacks... In short, much more like 21st century warfare than 19th...

James Nicoll: Since it takes months to years to cross the system and since rocket flares are visible across the system, the target knows you are coming.

This raises interesting questions about what sort of conflict could arise in the first place. The last time I was working on an interplanetary war story idea, I struggled to wrap my mind around the human aspect of launching an attack which wouldn't even reach the battlefield for months.

However, in my story idea, I assumed the two sides (Earth and the Martian colony) had no military spacecraft at all at first, because no one considered an interplanetary conflict a serious possibility. In your proposed assumptions, the political situation is far more volatile. Your situation is more like the historical situation during the age of sail.

If you look at the naval conflicts of the age of sail, the most important principle is the close blockade. Ships move so slowly that if you're not already where you need to be it's too late. Perhaps a similar principle could be applied to your Solar System. All of the major military powers could have expeditionary fleets which patrol close to potential troublespots.

James Nicoll: Am I right in thinking that this makes for an extremely lossy battlefield? Ten men go in, half a man comes out sort of thing?

Not necessarily. Because you can always see where the enemy is, it may be difficult to engage a force which knows it can't win. A force which is hopelessly outgunned may choose to retreat while still out of weapons range. A lot depends on the nature of the technology and how easy it is to gauge an enemy fleet's capabilities. For example, if we assume that the cost of weapon systems is small compared to the cost of drive systems, then it's a safe bet that any warship is heavily armed. On the other hand, if the cost of weapon systems is high compared to the cost of drive systems, then there could be a lot of lightly armed "dummies" to confuse matters.

Also, consider the "close blockade" principle. The tide of warfare might be determined almost entirely by strategic maneuvers BEFORE any declaration of war. The various sides move their chess pieces around the Solar System, hoping to gain some advantageous position in case of an outbreak of hostilities. Of course, if one side achieves a sufficiently advantageous position of forces, this might prompt the start of a conflict itself!

In this case, the true "conflict" is surprisingly peaceful most of the time despite the deadliness of the weapons involved.

Isaac Kuo: A force which is hopelessly outgunned may choose to retreat while still out of weapons range.

The superior force then has the option to pursue, or simply force the inferior one to run away long enough that it can't get home -- if you run out of fuel moving at 60 km/s, you're on your way to Arcturus. However, if payloads are variable (as in your game concept) and some ships have more delta-V than others, then how long do you pursue?

Isaac Kuo: For example, if we assume that the cost of weapon systems is small compared to the cost of drive systems, then it's a safe bet that any warship is heavily armed. On the other hand, if the cost of weapon systems is high compared to the cost of drive systems, then there could be a lot of lightly armed "dummies" to confuse matters.

Drive and weapon systems somewhat overlap at these performance levels. Anything moving at 30 km/s relative to its target is a weapon if it can be guided. As to how expensive guidance systems are...James? If guidance is cheap, then a side facing a stronger approaching force of warships will just load its merchant ships with guided buckshot payloads and expend them as necessary in order to to win.

Possibly the main design difference between merchant craft and war craft is that merchies are built to slow down and dock, warships to strike. I wouldn't expect most warships to be manned at all. For one thing, the delta-V is four times greater if you want to return home after a strike mission; a returnable warship is bound to be weaker for a given mass/cost. You might get a 'fleet' that amounts to a flock of cruise missiles — or IPBMs — just busses for kinetic weapon systems. At 30 km/s, every kilogram's mass of the strike group is packing 450 megajoules of kinetic energy (KE), and in the solar ecliptic, even every dirtside target can be 'on the near side' at impact (if you time the launch right).

Alternatively, perhaps you could have busses placed into retrograde 'parking' orbits matched to their potential targets — depending on how many were deployed, the delay time could be reduced to a couple of weeks. Of course these strike groups are also potentially subject to attack themselves every couple of weeks; KE cuts both ways.

Isaac Kuo: The various sides move their chess pieces around the Solar System, hoping to gain some advantageous position in case of an outbreak of hostilities.

The best defensive 'chess pieces' might be unmanned kinetic interceptors that are prepositioned along approach trajectories (although depending on orbital mechanics and delta-V, this might not work any better than launching them at need). If they can be maneuvered onto the track of an approaching fleet, they'll be able to strike hard while expending little delta-V of their own.

Maybe the long term weapons are robot solar-powered ion jets that latch onto small interplanetary objects (< 1 ton) and gradually nudge them onto potential attack trajectories. Or, shatter a small asteroid with a nuke, and attach mass-produced booster units to the spreading cloud of ammunition. If there are any asteroid mining ops, they already have lots of rocks to throw. (ed note: refer to the mention of "orbit guard")

Jonathan Cresswell-Jones: The superior force then has the option to pursue, or simply force the inferior one to run away long enough that it can't get home — if you run out of fuel moving at 60 km/s, you're on your way to Arcturus.

The obvious strategy is to run away in a safe direction. A greatly superior force coming from multiple directions could force a confrontation, but this is implies an extreme disparity in force strengths. Given such a disparity, it is plausibly obvious to both sides what the outcome of the battle would be. The inferior force could plausibly just surrender rather than pointlessly fighting to the death.

Jonathan Cresswell-Jones: Possibly the main design difference between merchant craft and war craft is that merchies are built to slow down and dock, warships to strike.

I imagine the main difference would be sensor and command systems. A merchant craft doesn't even need a crew or much of an onboard AI. Light speed delays don't matter because the only time they need a tight feedback loop is when they're within a "friendly" planetary system.

In contrast, a warship fleet needs to have sophisticated integral decision-making capabilities. This plausibly means on board crew although it could mean sophisticated AI. Light speed delay concerns dictate that the fleet needs to have its own sensor systems also. While the "sensor net" is good enough for strategic maneuvering, the fleet needs real-time information in a battle.

Also, a warship may have superior maneuvering capabilities. A merchant ship can live with just a single low thrust rocket. It never needs to make emergency maneuvers to dodge projectiles. On the other hand, it's desirable to limit the ship's hull to low thrust levels to minimize dead weight. In contrast, a warship could have a high thrust rocket, or a multi-mode rocket, or auxiliary rockets to facilitate high thrust maneuvers. It may have a beefier hull to deal with high thrust stresses. This depends on whether high thrust capability is militarily significant, of course.

Jonathan Cresswell-Jones: The best defensive 'chess pieces' might be unmanned kinetic interceptors that are prepositioned along approach trajectories.

You can simply launch them at need. In fact, if there are no enemy forces patrolling your sector, you may be able to afford to BUILD THEM at need.

But you misunderstand the idea of the "close blockade". The idea is to patrol all potential trouble spot sectors so you don't have to wait weeks or months before reacting to a situation. Your expeditionary fleets are already in place to react immediately to the outbreak of hostilities.

Isaac Kuo: The obvious strategy is to run away in a safe direction.

Well, the point was that if the defender gets driven to fuel exhaustion, there is no safe direction; you can't slow down. Maybe another friendly force (or negotiated neutral) could match velocities and rescue you, but unless they were set up for it in advance, it'd be tricky.

Now, here's where a high-KE kamikaze fleet has a problem — if the defender sidesteps somehow, the attacker may not be able to decelerate, come back, and resume the fight.

Isaac Kuo: But you misunderstand the idea of the "close blockade". The idea is to patrol all potential trouble spot sectors so you don't have to wait weeks or months before reacting to a situation.

Isn't that a division in detail, though? Of course, a player doesn't have to place fleets in all sectors. Each player would tend to 'patrol' the regions that they had vital interests in, and would have to think hard about committing force to others.

The lack of any stealth is a curious aspect. You can't sneak up on an opponent; if you redeploy some of your warships to gain local superiority over Player X's forces at one spot, everyone sees them moving into position. Depending on how predictable combat is (i.e., a 2-to-1 superiority means the weaker side is wiped out at little cost), simply sending more warships to one area could force a weaker, neutral player to either match the upgrade by dispatching their own reinforcements; start a fight immediately at even odds; sit tight and stare you down despite the new odds that would allow you to win handily if you start a fight; or withdraw. If there are three or more players' forces in one spot, then diplomacy/treachery will be decisive. "Oh, by the way, these arriving forces aren't to attack B — I just made peace with B this morning. They're to attack you."

On the other hand, "weapons outstripping defenses" implies a non-Lanchester equation: i.e., if 100 A units engage 50 B units, maybe there are only 50 A's left alive after the (very short) battle, not the 90 A's you'd expect if the units had some staying power. No stealth for moving attacks, but surprise treachery attacks would be deadly.

If Earth's balkanized as per James' post, then there could be several major Earth-based players who have large production and military capability, but are a long way from the outer system's points of interest. Suppose one Earth player has interests in the Unobtanium Mines of Io. If they station a permanent force there, it needs to be strong enough to defeat local forces, but it's too far away from home to count as a defensive force for the player if their interests are threatened back home — it's a write-off in some ways. Too many like that, and you might get attacked by another Earth player with more strength available at hand. If you send a mobile force, then it too must be (a) strong enough to not be a tempting target for an ambush en route by a hostile player; (b) still weak enough to afford to be 'out of play' for a year or two.

It might be cheaper to pay tribute to a distant local power, rather than to keep a squadron there. This is a bit like the 19th-cen Barbary Coast, where the US Congress voted for years to pay tribute to local rulers, rather than to build and deploy a more expensive navy. If the local-power player gets too greedy, they get spanked.

James Nicoll: Am I right in thinking that this makes for an extremely lossy battlefield? Ten men go in, half a man comes out sort of thing?

Well, since every unit in a battle can be shooting, it'll approximate the Lanchester square law (your losses are inversely proportional to your initial strength) - much like classical naval war. So basically I'd think that would be a good source of analogies. >(The main difference being the "see the enemy coming six months in advance" part, so no surprise attacks.)

James Nicoll: Am I right in thinking that this makes for an extremely lossy battlefield? Ten men go in, half a man comes out sort of thing?

Alternately, you don't send in your men until you have a hundred to the enemy's ten. Lots of staring across No Man's Space, feints to try and convince the enemy to misdeploy his forces, very occasional concentrated attacks against targets the enemy has left inadequately guarded.

Having an edge in strategic mobility is going to be important; the enemy can see your forces converging on a particular target, but can't quite do anything about it. Except, perhaps, counterattack somewhere else.

Having a 2:1 edge in strategic mobility is huge. You can concentrate your forces for an attack on any particular target, take or destroy it before reinforcements arrive, and still get back home (or wherever) ahead of the counterattack the enemy launched while you were away.

Both of the above assume that mobile forces contribute substantially to local defenses. If relatively immobile weapons platforms (surface or orbital) win over armed spaceships representing a much larger investment, you're back to stalemate.

Tactics: If one side has a clear advantage in both tactical mobility and weapons range, they win. On the other hand, some weapons don't allow for an absolute range advantage. And the defender will probably have the edge in tactical mobility, as he starts with full tanks and can burn it all.

Balkanized Earth may well be the battlefield of choice. If it's balkanized, even spaceborne parties to a conflict will likely find proxies there, and stealth and surprise are almost certainly still possible in the place crowded with friends, enemies, neutrals, oceans, jungles, mountains, and cities. Plus, it's likely to be the single greatest concentration of wealth in the Solar System until the time comes to dismantle it for raw materials, so un-balkanizing the Earth in one's own favor is, if possible, a winning strategy.