The battle of the Ouche (500 AD) was a victory won by Clovis, king of the Franks, during an otherwise unsuccessful intervention in a Burgundian family dispute.
By around 500 AD Clovis ruled a large part of northern Gaul. He had inherited a smaller kingdom based in Flanders and had successfully expanded into the area north of the Loire, and may also have conquered the Alemanni. The Burgundians were now one of his southern neighbours, with a kingdom based on the Rhone (although without access to the sea).
The Burgundians didn't have a single monarch during this period. King Gundowech (or Gondioc) had ruled until his death in 473. He was followed by his brother Chilperic I, but also left four sons - Gundobar (or Gundobad), Godegesil, Chilperic II and Godomar - who appear to have shared power with Chilperic I. Their uncle was Ricimer, one of the last men to hold real power in the Western Roman Emperor. Gundobar had briefly succeeded to Ricimer's position, but left the Roman court in 473 or 474 to return home. According to Gregory of Tours Gundobar promptly killed two of his brothers (Godomar and Chilperic II), and so after the death of Chilperic I in 480 only had to share power with Godegesil.
Clovis had a direct connection to the Burgundian royal family. His wife Clotilde was the daughter of Chilperic II, and so if Gregory's story is correct will have had little love for Gundobar. Although Gregory of Tours doesn't provide a date for this conflict the chronicle of Marius Aventicensis (written around 581) dates the battle to 500 AD.
By 500 Gundobar and Godegesil were at war with each other. Perhaps inevitably one of the brothers turned to their powerful neighbour Clovis for aid - in this case Godegesil, who promised to pay an annual tribute if Clovis helped him either kill his brother in battle or expel him from Burgundy.
Clovis accepted this offer and led his army into Burgundy. Gundobar was unaware of his brother's role in this, and sent a message to him suggesting that they should unite against the Frankish invader. Godegesil promised to come to his aid, but when the three armies came together on the River Ouche, Godegesil revealed his true colours and sided with Clovis. The allies crushed Gundobar's army, but Gundobar himself escaped and fled south to Avignon.
In the aftermath of this battle Godegesil promised to give Clovis part of the kingdom, and then left to enter Vienne in triumph. This would prove to be a fatal mistake. Clovis pursued Gundobar and besieged Avignon. Godegesil would have been wiser to accompany Clovis. Avignon held out against Clovis, who didn't have a siege train. One of Gundobar's advisors pretended to desert him, and convinced Clovis to accept an annual tribute in return for leaving Gundobar as joint king of the Burgundians. Once Clovis was gone Gundobar turned on his brother and besieged him at Vienne (c.500-501). The city fell and Godegesil was killed. Gundobar and Clovis appear to have been reconciled at some point after this, and the Burgundians probably supported Clovis during his later war against the Visigoths.