Childe Cycle # 4: Tactics of Mistake by Gordon R. Dickson

It’s obvious that Cletus Graeme–limping, mild-mannered scholarly–doesn’t belong on a battling field, but instead at a desk working on his fourth book on battle strategy and tactics. But Bakhalla has more battlefields than libraries, and Graeme sees his small force of Dorsai–soldiers of fortune–as the perfect opportunity to test his theories. But if his theories or his belief in the Dorsai lead him astray, he’s a dead man.