The Chi Rho is one of the first Christian cruciform symbols. It’s made by combining the first two letters of the Greek word “Christ,” chi = ch, and rho = r. The Chi Rho, while not strictly a cross, alludes to Jesus’ crucifixion as well as his status as the Christ. Constantine’s usage of the Chi Rho symbol on the labarum, the imperial standard, in the early fourth century CE is the oldest indication of its existence. On the eve of the Battle of the Milvian Bridge in 312 CE, Constantine had a vision of God in which he was directed to mark his men’s shields with the Chi Rho symbol, according to Lactantius, a fourth-century Christian apologist. The Chi-Rho became the official imperial insignia after Constantine’s victory at the Milvian bridge. Archaeologists have discovered evidence that the Chi Rho was imprinted on Constantine’s helmet and shield, as well as the shields of all of his men. The Chi Rho appeared on coins and medallions issued under Constantine’s reign. The Chi Rho was first employed on Christian sarcophagi and frescoes around 350 CE. [A.E.M.]