The battle of Vouille (507) was a significant victory for Clovis I, king of the Franks, and allowed him to conquer Aquitaine, taking it from the Visigothic kingdom of Toulouse. The Franks and Visigoths had been neighbours since Clovis's conquest of the last Roman enclave in northern Gaul (battle of Soissons, 486). The border was on the Loire, with Clovis to the north and Alaric II of the Visigoths to the south. Alaric's kingdom also included Provence, Septimania (the western part of the Mediterranean coast of Gaul) and large part of Spain. There may have been an earlier conflict between the two rulers that ended in 502, but that isn't entirely clear. Neither is the reason for the outbreak of war in 507, although Gregory of Tours states that the newly converted Catholic Clovis wanted to overthrow the Arian Visigoths.
King Theodoric of the Ostrogoths made a serious effort to prevent the outbreak of war. One set of ambassadors was sent to Alaric to try and convince him not to fight. They were then to move on to visit King Gundobar of Burgundy, in an attempt to convince him to help the peace efforts. A second set of ambassadors were sent to Clovis, but Theodoric wasn't a neutral peacemaker and in his letter to Alaric stated that 'your enemy will be mine also'.
According to Isidore of Seville Clovis was aided by the Burgundians. Gregory of Tours doesn't mention them in his account of the battle, although this may reflect his bias against the Arian Burgundians. It is also possible that the Burgundians advanced separately into Provence, while Clovis advanced further to the west. We do know that Clovis was supported by Chloderic, the son of Sigibert the Lame, king of the Ripuarian Franks
Alaric also had a mixed army, with Visigoths and Roman troops, including a contingent led by Apollinaris, the son of the Roman author and bishop Sidonius Apollinaris and others led by the leading senators of Auvergne. Theodoric the Great, the Ostrogothic King, had promised his support but he was delayed in Italy and wasn't able to send help until the following year.
The battle took place at Campo Vogladense - the plains of Vogladense, located at the tenth milepost outside Poitiers. This is normally considered to be Vouille, which is about the right distance to the west/ north-west of Poitiers, but other locations have been suggested.
Gregory of Tours was clearly not a fan of the Visigoths, and on more than one occasion characterised them as timid or cowardly. One example came after the battle of Soisson (486), when the defeated Roman general Syagrius fled to King Alaric seeking refuge. He was returned to Clovis, apparently because it was the 'fashion of the Goths to be terrified'. At Vouille the Goths are described as having 'fled as was their custom'. This is a rather unfair description of the Goths and one that isn't really supported by the location of the battle close to Poitiers, in the north of Alaric's extensive kingdom.
Gregory provides a rather frustrating account of the battle. One army is said to have fought from a distance while the other preferred close combat, but it isn't at all clear which army was which! The battle ended with the Goths fleeing and the death of King Alaric, probably during the pursuit. Clovis himself was nearly killed during this part of the battle when he was attacked by two lance-armed Visigoths. Clovis was saved by his coat of mail armour and fast horse, an interesting insight into the equipment of at least the very highest levels of the Frankish army.
After the battle Clovis moved south into Aquitaine, spending the winter at Bordeaux. The Visigothic capital at Toulouse was plundered, and early in 408 Angouleme was captured. Clovis then returned north to Tours, where he celebrated both his victory and the award of an honorary consulship by the Eastern Emperor Anastasius. Aquitaine became part of Clovis's kingdom, which he now ruled from Paris. Over the last few years of his life he seems to have concentrated on eliminating any rival Franks, including his allies Sigibert and Chloderic.
Although Clovis had won a major battle and killed Alaric, his victory wasn't total. The survivors of the army retreated to Narbonne, while the Spanish part of the Visigothic kingdom was never threatened. The defeat did trigger a succession dispute between two of Alaric's sons, with the army supporting Gesalic and Theoderic supporting Amalaric (Alaric's son and Theoderic's grandson).
In 508 Theodoric sent an army across the Alps, raised the Burgundian siege of Arles and expelled them from the former Visigothic lands. He then absorbed part of Provence into his kingdom, and secured the rest for Amalaric. Theodoric's men also forced Gesalic into exile, before defeating and killing him on his return to Gaul.