Dorsai!. The Childe Cycle Book 1

Donal Graeme set out to re-shape the galaxy, but first he must tear it apart. Donal Graeme, Dorsai of the Dorsai, was the final link in a long genetic train, the ultimate soldier, whose breadth of vision made him a master of space war and strategy - and something even greater. He was the focus of centuries of evolution, the culmination of planned development, and through him a new force made itself felt.
Dorsai were renowned throughout the galaxy as the finest soldiers ever born, trained from birth to fight and win, no matter what the odds. With Donal at their head they embarked upon the final, impossible venture: they set out to unify the splintered worlds of Mankind.