The Battle of Tolbiac was fought between the Franks under Clovis I and the Alamanni, traditionally in 496. The site of "Tolbiac", or "Tulpiacum" is usually given as Zülpich, about 60km east of the present Belgian frontier, which is not implausible.
The Franks were successful, and established their hegemony over the Alamanni. Clovis is said to have attributed his success to a vow that he had made: if he won, he would convert to the religion of the Christian God who had aided him. He became a Christian in a ceremony at Reims in 496.