Battle of Herbsthausen

The Battle of Herbsthausen, or the Battle of Mergentheim, was fought on May 2, 1645. The battle was between French forces led by Marshal Turenne and the Bavarian army led by Franz von Mercy. The French had caught the Bavarians short of troops at the beginning of the campaigning season, and pursued the Bavarians deep into Württemberg, but the Bavarians caught the French unawares and heavily defeated them.

Preliminaries
At the beginning of the 1645 campaign season, 4,000 troops had been detached from Mercy's army in order to reinforce the army of the Holy Roman Empire against the Swedes. Upon learning this, Turenne moved to immediately bring Mercy to battle, pulling approximately 11,000 men and 15 guns from winter quarters and marching on Württemberg, in which vicinity Mercy was encamped. Turenne drove Mercy and his 6,000 men steadily deeper into Germany, from Stuttgart to Halle to Mariendal, where he finally encamped to await reinforcements from the Hessians and collect forage for his horses. His forces were dispersed into encampments in villages in the vicinity.

Battle
At 2:00 am on May 2, Turenne was awoken to the news that Mercy was bearing down on the French encampments. Turenne issued orders to the army to regroup at Herbsthausen and for General Rosen to rally the forces there. Ignoring the advantageous terrain that he was in possession of, and heedless of his still inferior numbers (he had but 3,000 men at this time), Rosen deployed his battalions on the plain near Herbsthausen, where Mercy found him and, sensing his advantage, issued only a desultory artillery bombardment before attacking with his cavalry and infantry. Turenne arrived too late to reverse Rosen's errors, and Mercy's forces overwhelmed the French.

Consequences
All of Turenne's infantry was lost, as well as most of his cavalry. Turenne himself narrowly avoided capture, and fled to Hesse-Cassel to avoid Mercy's close pursuit. Cardinal Mazarin now found it necessary to commit d'Enghien (the later Great Condé) to the campaign to rectify the French position in Western Germany, which led to the Second Battle of Nördlingen in August, where Mercy was killed.