And in 450 Attila had proclaimed his intention of attacking the powerful kingdom Visigoth of Toulouse in alliance with Emperor Valentinian III . Attila had previously been in good relations with the Western Empire and its de facto ruler, Flavius Aetius . Aetius had spent a brief exile among the Huns in 433 , and the troops Attila had provided against the Goths and the Burgundians had helped to get the title "honorary" mostly of "magister militum" in the West. The gifts and diplomatic efforts Genserico , who opposed and feared the Visigoths, could also affect the plans of Attila.
In any case, in the spring of 450, Valentinian's sister, Honoria , which had involuntarily engaged to a senator, a Hun king sent for help along with his ring. Although it is likely that Honoria had no intention of proposing marriage, Attila chose to interpret his message as well. He accepted, asking dowry half of the Western Empire. When Valentinian discovered what happened, only the influence of his mother, Gala Placidia , Honoria got sent into exile rather than kill. Attila wrote categorically denying the legitimacy of the alleged offer of marriage. Attila, without being convinced, sent an embassy to Ravenna to proclaim the innocence of Honoria and legitimacy of its proposed betrothal, and that he himself would come to claim what was rightfully theirs.
Meanwhile, Theodosius died after falling from his horse and his successor, Marciano , stopped paying tribute in late 450 . The successive invasions of the Huns and other tribes had left the Balkans with little to plunder. The King of the Salian had died and the succession struggle between his two sons led to a clash between Attila and Aetius. Attila supported the elder son, while Aetius did the baby. Bury believes that Attila's intent to march westward was to extend his kingdom-and then the most powerful continent-to Gaul and the shores of the Atlantic . For when assembled all his subjects ( Gepids , Ostrogoths , rugianos , escirianos , Heruli , Thuringian , Alans , Burgundians , etc.) and began his march westward, had already sent alliance offers both to the Visigoths and the Romans.
In the 451 arriving in Belgium with an army estimated at 500,000 men Jordanes soon became clear what his true intentions. On April 7 took Metz , forcing Aetius to get moving to cope with troops recruited among the Franks , Burgundians and Celtic . An embassy of Avitus , and Attila the steady progress westward convinced the Visigoth king, Theodoric I , to ally with the Romans. Their combined army reached Orleans ahead of Attila, cutting off his advance. Aetius chased the Huns and chased them around Chalons-en-Champagne , locking the battle of the Fields Cataláunicos , which ended with the victory of the Gothic-Roman alliance, but Theodoric was killed in combat. Attila retreated beyond their borders and their allies were disbanded.