The Cursed by Barry Sadler (Casca Series, Book 18) from Books In Motion.com

Casca Longinus. Cursed by Christ on Golgtha. Condemned to outlive the ages, and wander the globe a constant soldier. Forever fighting, surviving, waiting for Christ to return. In this book, it is the turn of the century in colonial China, and Casca is a British soldier with a choice: a suicide mission, or the agony of death on the gallows. To avoid the rope, he must penetrate the heart of the mysterious land and bring back word of the impending revolution. Captured and tortured by a warlord, his true identity is revealed. They call him Cas-Ca Sho (Of Long Life)and proclaim him a count. Now he must lead an army of a million subjects into the slaughter of revolt against the British.