The Battle of Mainz was fought between the Franks and an alliance of Vandals, Suevi and Alans and took place on 31 December 406. The battle was won by the Vandals and Alans, and cleared the way for their invasion of Gaul.
The battle is briefly described by Gregory of Tours in his History of the Franks. According to his account, the Franks ambushed the Hasdingi Vandals as they were crossing the Rhine, and killed their king, Godigisel. The Vandals were rescued by the Alans under Respendial, who drove back the Franks.
Coordinates: 50°00′00″N 8°16′00″E / 50.0000°N 8.2667°E / 50.0000; 8.2667
The Battle of Mainz (29 October 1795) saw a Habsburg Austrian army led by François Sebastien Charles Joseph de Croix, Count of Clerfayt launch a surprise assault against four divisions of the French Army of Rhin-et-Moselle directed by François Ignace Schaal. The right-hand French division fled the battlefield, compelling the other three divisions to retreat with the loss of their siege artillery and many casualties. The War of the First Coalition action was fought near the city of Mainz in the state of Rhineland-Palatinate in Germany.
French troops had ineffectively besieged the western side of Mainz Fortress since December 1794. However, in early September 1795 the Army of Sambre-et-Meuse crossed the lower Rhine River and advanced south to the Main River. For the first time Mainz was besieged on the east side of the river, but this state of affairs did not last very long. In the Battle of Höchst, Clerfayt outmaneuvered Jourdan, forcing his army to retire to the west bank of the Rhine. With Jourdan temporarily out of the picture, Clerfayt fell on Schaal's somewhat isolated corps and drove it away to the south. During this time the commander of the Army of Rhin-et-Moselle, Jean-Charles Pichegru was in treasonous contact with France's enemies, perhaps accounting for Austria's success. The next clash was the Battle of Pfeddersheim on 10 November.