 Constantine recognized the implicit danger in remaining at Galerius 's court , where he was held as a virtual hostage . His career depended on being rescued by his father in the west . Constantius was quick to intervene . In the late spring or early summer of 305 AD , Constantius requested leave for his son to help him campaign in Britain . After a long evening of drinking , Galerius granted the request . Constantine 's later propaganda describes how he fled the court in the night , before Galerius could change his mind . He rode from post @-@ house to post @-@ house at high speed , hamstringing every horse in his wake . By the time Galerius awoke the following morning , Constantine had fled too far to be caught . Constantine joined his father in Gaul , at Bononia ( Boulogne ) before the summer of 305 AD . 
