Don't know about a must read of biographies (there are so many).
However books that I would recommend:
Macrcus Aurelisus Meditations -the Gregory Hays translation was professionally done
Cicero - On Government
In The Company of Soldiers by Rick Atkinson, a good read following the 101st and the invasion of Iraq
The Sharp End: A Canadian Solider's Story by James R. Davis, a good autobiographical account of the Canadian military - served with the guy and to be honest it's a good read.. my copy is currently in Iraq somewhere
