If humans develop colonies we must plan for the possibility of armed rebellion/takeover on both sides. To prepare for this we should look at how space battles would be fought. First of all, explosives could not be used. Explosive devices, nuclear of conventional, are effective because they produce a shock wave that destroys the surrounding area. In space there is no air to push away so the energy of the explosion would dissipate harmlessly. Instead humans would likely use kinetic impactors, or lasers. Kinetic impactors are basically bullets that are shot at very high velocity toward enemy ships with the intent to pierce their armor and damage critical systems. The problem with these weapons can be seen by studying Newton's 3rd law, the energy imparted into the projectile would create a force on the attacking ship in the opposite direction which would make it an easy target for enemy ships which could predict this change in direction. An alternative weapon would be a high powered laser. Laser's have an advantage in space because they will effectively go on forever with very little diffraction. Unfortunately lasers shoot energy and therefore require large amounts of it which is hard to get in space. This means that only small lasers could be used. Also lasers create a lot of heat at the target, which is good, and the base which is bad. Without an atmosphere to distribute heat the lasers could only fire intermittently and even then would require large radiators to dissipate heat.