In the Austro-Prussian War of 1866, Werder greatly distinguished himself at Gitschin and Königgratz at the head of the 3rd Division. He returned home with the rank of lieutenant-general and the Order Pour le Mérite. In 1870, at first employed with the 3rd Army Headquarters and in command of the Württemberg and Baden forces, he was after the Battle of Wörth entrusted with the operations against Strasbourg, which he captured after a long and famous siege.