 In the late 4th century, his functions were limited to Britain, while the fortifications in Gaul were established as separate commands, dux tractus Amoricani and dux Belgicae Secundae, with headquarters at Portus Aepatiaci (possibly Étaples).In Gaul, the Franks, a fusion of western Germanic tribes whose leaders had been strongly aligned with Rome since the 3rd century, subsequently entered Roman lands more gradually and peacefully during the 5th century, and were generally endured as rulers by the Roman-Gaulish population.The Franks became foederati in 358 AD, when Emperor Julian let them keep the areas in northern Gaul, which had been depopulated during the preceding century.