The mountain peak was a strategic area bitterly fought for by both sides. The most severe fighting for the peak took place on 19–20 January, 26 March, 25–26 April and 21–22 December 1915. Amongst the casualties was General Marcel Serret, commander of the 66th Infantry Division. After about 11 months of fierce combat, both sides began to focus most of their attention farther north on the Western Front. Only enough men to hold the lines were left at Hartmannswillerkopf. The lines remained relatively stable for the remainder of the war and generally only artillery exchanges took place. 30,000 died near Hartmannswillerkopf during the First World War, with the majority of deaths suffered by the French.