The Prince's Alliance by Christopher G Nuttall

Prince Roland was on the verge of winning the war.

Assigned to New Doncaster to train the planet's armies and lead them into battle, Roland brokered a political compromise that allowed the government to win hearts and minds once the rebels were defeated in the field, then built a formidable military machine that could – and did – push the rebels to the brink of defeat. But Roland's success bred hatred and his enemies, seeing him and his loyal troops out on a limb, launched a coup and left Roland stranded deep in enemy territory.

Roland isn't one to give up. But, with a government preparing to use desperate measures to obliterate the rebels on one side and a crude alliance of suspicious rebel factions on the other, he must act fast to save the planet ...

... Or watch helplessly as the civil war rages on.