 Complete the following phrase:  Flavius Julius Crispus ; c. 303  326 was the eldest son of the Roman emperor Constantine the Great and his junior emperor caesar from March 317 until his execution by his father in 326. The grandson of the augustus Constantius I, Crispus was the elder half-brother of the future augustus Constantine II and became co-caesar with him and with his cousin Licinius II at Serdica, part of the settlement ending the 