Flavius Claudius Constantinus was born in 316 and was the eldest son of Constantine I. In 317 Constantine made his child Caesar at age one and later led him into battle against the Sarmatians at age 7.
After the death of his half brother Crispus, he took over the role of commander of Gaul at age 10 and in 332 his father elected him as commander of the army in their battle against the Goths.
When his father died in 337, he became co-emperor along with his two brothers Constantius II and Constans and after they divided the empire among them he regained rule over Gaul along with Britannia and Hispania.
Along with his rule of these regions he was also designated guardian of Constans, his younger brother, who had rule over Italia, Africa and Illyricum but even when Constans came of legal age Constantine refused to release guardianship and in 340 declared battle against his brother.
Constantine II was killed and Constans gained control over regions previously ruled by his brother.