The superimposed Greek letters chi and rho, the first two letters of Christ’s name, was a popular early Christian symbol. The monogram of Christ, or chrismon, is also a powerful symbol of imperial victory: it appeared to Emperor Constantine the Great before his battle against Maxentius in ad 312, promising victory in the name of Christ. Made of gold sheet and decorated with three garnets, it may have formed the center of a golden wreath, serving as a protective device and an emblem of Christian triumph.