It's not for nothing that spies are shot in wartime. Secrecy is often a matter of life and death and the ability of the computer to keep you in the dark most of the time accurately recreates this aspect of warfare. On the down side, this makes pre-play analysis of the game more difficult than is the case with manual games. Saving the Game- Next to the hassle of setting up the game, manual wargames are also wretched when you want to put aside a game to finish later. The map is a large object and all those playing pieces can be easily displaced.
Computers suffer no such problems.
Press the right key and your game in progress is saved to a disk. You can take it up again whenever you want. A computer is very good at computing, and keeping track of things. Manual wargames always suffered when burdened with too much record keeping. Yet data, and calculation, is what makes a wargame different from chess and capable of recreating history.