What would interstellar war really look like? Part 2 - Strategy

Almost a year ago, I started looking at what interstellar war might actually look like, and initially considered the economic conditions that might make such a war possible and more likely to occur. In it, I suggested that a practical maximum transit time from centre to edges of an interstellar economy would be in the region of 1 year, before fighting for anything became worthwhile. That led to the conclusion that a minimum requirement was a faster-than-light drive capable of speeds at least 100 times the speed of light.

The next step to consider is what the strategic considerations of an interstellar war might be: how would victory be measured, and what overall objectives would lead to achieving it?

Taking, again, as our starting point the idea that most wars are in some way fought for economic reasons - to gain or keep possession of resources, or the means to acquire those resources - then victory comes when the other side cannot viably wrest control of the desired resources from one's own side, or when the other side makes the calculation that they can no longer do so (and therefore, surrenders). In past conflicts, this has been achieved by destroying the other side's means to make war, or else by maintaining a sufficiently strong military presence as to deter attempts at retaking resources. Usually, the two go hand-in-hand; as a nation's armed forces are depleted, then it takes a smaller force to convince them that they cannot mount an effective attempt to retake lost territory.

An army's ability to make war depends essentially on its ability to obtain new supplies. The essential ingredients for an effective fighting force, before we get to anything else, are: food and water for the troops; weapons, and ammunition for the weapons; means of transport, and fuel for the means of transport. Supply lines are nearly always a key point of a war, which is one reason why guerilla war often involves sabotage of supply points.

At this point, it becomes necessary to consider not just the minimum requirements, but other possibilities for transit methods, since these can have a big effect on the types of supply lines that interstellar war would have.

I am going to consider two different approaches to solving the problem of interstellar travel that have been posited by various science fiction writers. I am going to call these the "near-instant transit system" (NITS) type and the "natural space flight" (NSF) type.

NSF refers to the more commonly proposed system, whereby starships fly between solar systems using some form of faster-than-light drive but otherwise travelling in "normal space" (though how normal it is depends on the details of the fictional technology).

NITS refers to some system that appears to bypass "normal" space to travel instantly, or nearly instantly, between two points. The transporter beam in Star Trek is an example of a NITS, although it is not posited there as a means of interstellar travel, only as ship-to-ship or surface-to-orbit travel within a single planetary system. The most commonly suggested NITS is actually the use of wormholes to create shortcuts through spacetime between two worlds or two solar systems. Typically, a NITS is seen as being limited in range (as with the Star Trek transporter beam), due to the requirement of a central sending/receiving station from which goods and people depart and at which they arrive. The further one travels from the central station, the less practical the system becomes until there is a technological limit on how far it is possible to travel from the central station. At the extreme range, a new station might be built enabling one to string several transits together to increase the overall range from the origin point, which adds transit time as one has to travel from one's arrival point to ones departure point at the new system (or else, reset the system for the next stage of the journey)

Arguably, some versions of "hyperspace" drives combine the two. The system of hyperspace used in Isaac Asimov's "Foundation" saga allows a starship to travel instantaneously between two points in interstellar space. Flight time between worlds is a result of the time needed to calculate each jump (with longer jumps being more complicated) plus the time taken to travel into the solar system after arriving outside it.

In considering the minimum speed requirement, I was looking at NSF transit, for which I estimated that the maximum radius of an interstellar economy would be approximately 1 year of travelling time. As travelling times decrease, their significance decreases in terms of the requirements of supply lines, but the basic principle will remain fairly similar.

Interstellar space is big. Really, really big. It is also pretty empty as far as any form useful economic or military resources are concerned. It cannot realistically be controlled in any meaningful way to prevent transit through it between one point and another, without expending vast amounts of resources for very little gain. That means that in an interstellar economy based on NSF, then attempts to control supply lines will most often occur within solar systems, where the desirable resources are located and where it is much easier to try to impose blockades because the amount of space to be controlled is that much less, and detecting and intercepting enemy supply ships will therefore be that much easier.

There are two possibilities for an interstellar fleet seeking to control (either by capturing from the opponent, or by defending against an opponent) a solar system. The first is to rely on supplies being brought in by supply ships. The second is to rely mostly on using the resources that exist in the solar system itself. As transit times and costs decrease, the value of the first option increases. However, in much of military history, relying on the occupied territory to supply an army's needs has been the usual way of solving the supply lines problem. For example, Julius Caesar's War Commentaries describe how his legions in Gaul typically took what they needed from the local populace while conducting their wars against rebellious tribes. Similarly, the most likely way for an interstellar war fleet to be able to sustain itself is by being able to produce or acquire its own food, weapons, ammunition and fuel from the local environs. Resupply would only be used where these resources were not available in the local solar system. For instance, where the system's colony or colonies were purely mineral-wealth based, then food would not be obtainable easily and supplies from elsewhere would be needed; and a system that did not produce fuel would obviously leave the fleet short on that until supplies arrived for them. In general, we can say that the starships of the interstellar war fleet would need to be more or less self-sufficient, carrying (or producing on board) enough supplies each to conduct a campaign to take control of a solar system's resources, that they can then use to replenish themselves.

This gives us our first hint of the likely size of a starship, or at least of an effective war fleet. The US Navy's carrier battle groups have supply ships with them that carry food for about 70 days before they need replenishing. The current aircraft carriers in the US Navy carry about 5,700 people (including the air crew) and we don't yet know if a starship would need that many people. We also don't know for sure how long they might need to stay on duty in an enemy solar system. The key point is the transit time to the enemy solar system. As noted above, the maximum radius of the empire is likely to be 1 year travel time, or approximately 400 days (to 1 significant figure). Let us assume that there will be opportunities to resupply at other points besides the centre of the empire, so the ship will not need to carry quite as much food as that to get to its target. Even with these considerations, there is likely to be a need for several days to the target, and various activities before an assault is possible once the ships arrive in the target solar system. When considering starships, thinking in terms of size as being at least comparable to the combined volume of a US Navy carrier group looks like a good starting point, before we start to consider what sorts of operations the starships might have to carry out.

***

With a NITS based economy, transit time is much less significant because it is nearly instantaneous. The key point for NITS is that it is based on obvious bottleneck points: the base stations for sending and receiving goods and people.

It seems reasonable that for a NITS to be viable, it does not need a fixed arrival point. If it did, then there would be no way to establish the network other than to send the necessary technology via NSF to reach the destination point. This would very much reduce the efficiency and viability of the technology as the basis of a growing economy, and in terms of discovering solar systems for economically viable colonies would require a viable rival NSF option already functioning. Typically, the reason for having a receiving point is presented as making the network more cost-effective per transit, and making it more reliable in terms of landing in exactly the right place. An additional benefit for civilian and commercial use is that it provides a useful focal point and that retargeting the system for each passenger or cargo could be costly and time-consuming.

This means that using NITS for military deployments is practical (because the cost of retargeting will not be incurred as often, but only a few times for each operation), and also means that capturing a NITS base will not be enough to stop a solar system from being supplied from elsewhere (because the system only needs to be retargeted to once, to a new reception point, to break the siege). Capturing the base prevents supplies from being sent by the enemy, but not from being received. It does, however, offer the possibility of using the base to send one's own troops and supplies into a new combat area.

A NITS system therefore presents a great tactical challenge for any defending army, but those issues are for another essay. The key point here is the strategic value of taking control of NITS bases as the central element in the enemy's economy.

***

In this piece, I have discussed the likely points of strategic importance, and how the type of interstellar travel would affect which points are most important. In my next piece, I shall look more at the tactical elements, that is, how might the objectives discussed here be achieved?