Constantine (272-337 AD)

Flavius Valerius Constantinus was not born to rule alone. He was one of four co-emperors in Diocletian's Tetrarchy - a system designed to prevent any single man from holding all the power. It didn't work. Through a decade of civil war, Constantine eliminated his rivals one by one until only one obstacle remained. In 312 AD, he marched on Rome to face the emperor Maxentius at the Milvian Bridge. The night before the battle, he saw a vision in the sky.

What followed changed the Western world. Constantine defeated Maxentius, became sole emperor, and issued the Edict of Milan - granting religious tolerance throughout the empire and ending three centuries of Christian persecution. He founded Constantinople as a new imperial capital, convened the Council of Nicaea to unify Christian doctrine, and reoriented the entire Roman Empire toward a faith that would define Western civilisation for two millennia.

He put the Chi-Rho symbol on his soldiers' shields, marched into battle, and let history decide.