Battle of Castras (Fidem Pacis)

The Battle of Castras (French: Castres) was fought on the 8th October 640 between the Visigoths of Hispania and the combined forces of the Franks and the Western Roman Empire. It resulted in a decisive Visigothic victory and saw the permanent reconquest of Aquitania, the Goths having temporarily taken and then lost it again the previous summer.

Background
Aquitania had formerly been at the heart of the Visigothic kingdom, but the vast province was lost to the Franks in 507 after the disastrous Battle of Vouille. Ever since then the Goths had dreamed of retaking it, and in 639 they finally saw their chance.

In that year the Frankish kingdom had been engaged in wars on several fronts at the same time - against the Lombards in Italy, the Frisians in Germania, and the rebelling Alemanni at the headwaters of the Rhine. Aquitania was left almost undefended, and King Chintila took the opportunity to cross the Pyrenees and invade. However, after defeating the local levies, Chintila sickened and died, and his son Tulga had to return to Hispania to assert his claim to the throne.

By early 640 the Frisians and Lombards had been defeated. King Dagobert of the Franks, together with his ally Emperor Isaac of the West Romans, put together an expedition to reconquer Aquitania and punish the Goths. In March and April they defeated the Gothic garrisons of Augustoritum, Tolosa, Burdigala and Narbo Martius, then proceeded to invade Hispania itself.

Tulga had still not succesfully asserted his kingship, being challenged by the aged general Chindasuinth. Nevertheless he marched to meet the Franks and Romans, and was promptly defeated and killed a few miles from Caesaraugusta. The allies continued south, sacked Toletum in July, then began a slow return to Gaul, looting and pillaging as they went.

However, with his main rival dead, the Gothic nobles flocked to Chindasuinth's power base in Hispalis to swear allegiance. Chindasuinth immediately marched his army north to try and intercept the Franks, finally catching up with them just north of the Pyrenees.