He inherited a large portion of the Visigothic possessions in the Aquitaine region of Gaul, an area that had been under Visigothic control since 415. Over the decades the Visigoths had gradually expanded their holdings at the expense of the weak Roman government, advancing well into Hispania in the process.
Upon becoming king, Euric defeated several other Visigothic kings and chieftains in a series of civil wars and soon became the first ruler of a truly unified Visigothic nation. Taking advantage of the Romans' problems, he extended Visigothic power in Hispania, driving the Suevi into the northwest of Iberia. By the time the Western Roman Empire ended in 476 he controlled nearly the entire Iberian peninsula.
Previous Visigothic kings had officially ruled only as legates of the Roman Emperor but Euric was the first to declare his complete independence from the puppet emperors. In 475 he forced the western emperor Julius Nepos to recognize his full independence in exchange for the return of the Provence region of Gaul. The Roman citizens of Hispania then pledged their allegiance to Euric, recognizing him as their king. In the same year Clermont(-Ferrand) surrendered to him after a long siege, and its bishop, Sidonius Apollinaris, sued for peace. He divided the Western Roman Empire with Odoacer.
Euric was one of the more learned of the great Visigothic kings and was the first German to formally codify his people's laws. The Code of Euric of 471 codified the traditional laws that had been entrusted to the memory of designated specialists who had learned each article by heart.
At Euric's death in 484 the Kingdom of the Visigoths encompassed all of Iberia except for the region of Galicia (ruled by the Suebi) and more than two-thirds of modern France. Edward Gibbon, in Chapter 38 of the History of the Decline and Fall of the Roman Empire, remarks: