Labarum

• The Labarum was a Roman military standard bearing the symbol of Chi Rho, which Constantine I‘ soldiers always displayed going into battle.
• The Chi Rho Symbol consisted of the Greek letters ‘Chi’ (X), and ‘Rho’ (P), which were the first two letters of Christ’s name when spelt in Greek.

History

• Constantine I first made his soldiers paint the Chi Rho symbol on their shields at the Battle of Milvian Bridge in 312 CE.
• In all future battles, his soldiers carried the symbol on the Labarum.