Ash: A Secret History | Mary Gentle
For the beautiful young woman Ash, life has always been arquebuses and artillery, swords and armour and the true horrors of hand-to-hand combat. War is her job. She has fought her way to the command of a mercenary company, and on her unlikely shoulders lies the destiny of a Europe threatened by the depredations of an Infidel army more terrible than any nightmare. Winner of the BSFA Award for best novel, 2000