a SSD would increase battery life, also, for the purposes its being used, you need very little hard drive space. just the OS and a single program.
I'd imagine you can probably rig the thing up using a netbook
and if you are running a powerful enough wireless signal you could have more than enough range for the commander back at HQ to have real time tracking on where his units are.
and give commands via radio that could also be displayed on the map.
The squad leaders would be able to see where they need to go in relation to their position and scale the map as needed, instead of having to use a paper map.
So about the only things this needs to be a fully integrated combat system is a smaller screen, a longer battery life, and longer range wireless connection.