Answer:
The Chi-Rho symbol has a wreath around it, which symbolizes power of resurrection over death, symbolizing the life events of Jesus Christ that happened when he was crucified. The artwork also depicts a number of symbols that were used in the past, showing the culture.
During Milvian Bridge battle, Constantine and his soldiers were enlightened from a Christian god by a vision, which was interpreted by them that if the symbol was painted on soldier shields, victory was certain to come.
