The coming of suspended animation of advanced nanotech removed many of the logistical hurdles that military forces had faced for time beyond counting. Forces could go indefinitely without resupply, and troops could be packed for much easier transport and woken up for the battle. One of the applications of this has been "subcraft" tactics.
Subcraft are a type off gunship that, although no match for a front line warship or a hyperturing controlled swarm, are fully capable of handling less serious threats and supporting such warships. In the event that they encounter an enemy they cannot defeat the subcraft go into hiding. Fully triphibious as well as exoatmospheric, and equipped with sophisticated hyperturing nanostealth devices, they can enter almost any liquid or gaseous environment and remain indefinitely, the crew hibernating and nanotechnology maintaining the ship. Once the superior forces have left the area, the subships reactivate and attack the enemy forces that they can defeat.
Subships are almost always equipped with a compact fusion reactor that can be fired up and shut down at notice, and back up fuel cells. The main problem with early model subships was that the shielded radioactive hydrogen and helium isotopes (deuterium and tritium) required for a fusion reactor tend to decay, making long shutdowns unreasonable. Fortunately, deuterium can be extracted from seawater, and tritium from most gas giants, and of course modern designs are not dependent on radioactive isotopes.
The energy limitations mean that they depend much more on smart missiles than on energy beam weapons, and most Subships, while bristling with rockets, torpedoes, mines, and offensive khaki goo, have little more than a couple of light lasers and machine guns for close in attack/defence.
Although they need to be relatively small (to effectively hide from the enemy who will surely search for them), subcraft are relatively cheap and can be produced in great numbers. Even if they never get a chance to attack, the opposing power must leave ships in the system to guard against their attack - ships would would be better put to use fighting similar front line warships. This limitation on enemy logistics has resulted in more wars being won than the actual damage the ships do.
The technical points of distinction between Subcraft, Subships, and Lurkships, in terms of size, firepower, endurance, and so on generally differ from empire to empire, but generally a Subship is larger, and equipped with more potent stealth, intelligence and shielding and a Lurkship somewhat larger, more intelligent, and more potent yet again.
- Lurkship - Text by M. Alan Kazlev
Generally, a heavily armed and armoured, short-range hyperturing military vessel, capable of stealth operations in a hydrospheric and atmospheric environment for greatly extended periods of time. Subcraft or subships are similar but smaller and less well armed and equipped.