 Constantine the Great ( Latin : Flavius Valerius Aurelius Constantinus Augustus ; Greek : <unk> ὁ Μέγας ; 27 February c . 272 AD – 22 May 337 AD ) , also known as Constantine I or Saint Constantine ( in the Orthodox Church as Saint Constantine the Great , Equal @-@ to @-@ the @-@ Apostles ) , was a Roman Emperor from 306 to 337 AD . Constantine was the son of Flavius Valerius Constantius , a Roman army officer , and his consort Helena . His father became Caesar , the deputy emperor in the west in 293 AD . Constantine was sent east , where he rose through the ranks to become a military tribune under the emperors Diocletian and Galerius . In 305 , Constantius was raised to the rank of Augustus , senior western emperor , and Constantine was recalled west to campaign under his father in Britannia ( Britain ) . Acclaimed as emperor by the army at Eboracum ( modern @-@ day York ) after his father 's death in 306 AD , Constantine emerged victorious in a series of civil wars against the emperors Maxentius and Licinius to become sole ruler of both west and east by 324 AD . 
