Rampage at Waterloo — Brian Falkner

This alternative history re-imagines the 1815 Battle of Waterloo as a victory for the French emperor Napoléon Bonaparte, when he unleashes a terrible secret weapon - giant carnivorous survivors from pre-history - on his unsuspecting British and Prussian adversaries. In this world, smaller "saurs" are an everyday danger in the forests of Europe, and the Americas are a forbidden zone roamed by the largest and most deadly animals ever to walk the earth. But in his quest for power, Napoléon has found a way to turn these giant dinosaurs into nineteenth century weapons of mass destruction. Only Willem Verheyen, an outsider living in hiding in the tiny village of Gaillemarde, has the power to ruin the tyrant's plans. And Napoléon will stop at nothing to find him.

War is coming, and young Willem is no longer safe, for Gaillemarde is just a stone's throw from the fields of Waterloo -- fields which will soon run red with blood.