The Battle of Hartmannswillerkopf () was a series of engagements during the First World War fought for the control of the Hartmannswillerkopf peak in Alsace in 1914 and 1915. The peak is a pyramidal rocky spur in the Vosges mountains, about north of Thann, standing at and overlooking the Alsace Plain, Rhine valley and the Black Forest in Germany. Hartmanswillerkopf was captured by the French army during the Battle of Mulhouse 1914). From the vantage point, Mulhouse and the Mulhouse–Colmar railway could be seen and the French railway from Thann to Cernay and Belfort shielded from German observation.
The two French invasions and captures of Mulhouse by the French VII Corps ( Louis Bonneau) and then the Army of Alsace (General Paul Pau), were repulsed by the German 7th Army ( Josias von Heeringen). Both sides then stripped the forces in Alsace to reinforce the armies fighting on the Marne, Aisne and further north. For the rest of 1914 and 1915, both sides made intermittent attempts to capture Hartmanswillerkopf. The operations were costly and eventually after another period of attack and counter-attack that lasted into the new year of 1916, both sides accepted a stalemate, with a fairly stable front line along the western slopes that lasted until 1918.
Background
A few border skirmishes took place after Germany declared war on France; after 5 August, more German patrols were sent out as French attacks increased. French troops advanced from Gérardmer to the Col de la Schlucht (Schlucht Pass), where the Germans retreated and blew up the tunnel. The French VII Corps ( Louis Bonneau) comprising the 14th and 41st divisions, advanced from Belfort to Mulhouse and Colmar to the north-east, suffered supply difficulties but seized the border town of Altkirch, south of Mulhouse, with a bayonet charge. On 8 August, Bonneau cautiously continued the advance and occupied Mulhouse, shortly after its German defenders had left. In the early morning of 9 August, parts of the XIV and XV Corps of the German 7th Army arrived from Strasbourg and counter-attacked at Cernay; Mulhouse was liberated by German troops on 10 August and Bonneau withdrew towards Belfort.
Paul Pau was put in command of a new to re-invade Alsace on 14 August, as part of a larger offensive by the First Army and the Second Army into Lorraine. The began the new offensive against four German brigades, which fought a delaying action as the French advanced from Belfort, two divisions on the right passing through Dannemarie at the head of the valley of the Ill river. On the left flank, two divisions advanced with several battalions, which had moved into the Fecht valley on 12 August. On the evening of 14 August, Thann was captured and the most advanced French troops reached the western outskirts of the city by 16 August. On 18 August, VII Corps attacked Mulhouse and captured Altkirch on the south-eastern flank. By the evening of 19 August, the French had occupied the city, having captured and considerable amounts of equipment. With the capture of the Rhine bridges and valleys leading into the plain, the French had gained control of Upper Alsace but on 26 August the French withdrew from Mulhouse to a more defensible line near Altkirch, to provide reinforcements for the French armies closer to Paris.
Prelude
The was dissolved on 26 August and many of its units distributed among the remaining French armies. In September 1914, the German 7th Army was transferred to the Aisne and left three brigades in (Upper Alsace). On 19 September 1914, (An was an improvised force larger than a corps and smaller than an army, subordinate to an army headquarters.) named after its commander Hans Gaede (formerly the chief of staff of the XIV Corps) and renamed (Army Detachment Gaede) on 30 January 1915.
Battle
1914–1915
On 25 December, the French 66th Division and a battalion of attacked through deep snow and woods, to improve the French position on the peak of Hartmannswillerkopf. The French attack succeeded but the German defenders were pushed back only a short distance. Division of attacked on a line from Hartmannswillerkopf to the Herrengluh ruins, Wolfskopf and Amselkopf in thick fog from 18 to 21 January 1915 and managed to surround the French positions, recapturing the summit of Hartmannswillerkopf and Hirzstein to the south, a French counter-attack being repulsed. The main German attack on 30 January, near Wattwiller, made early progress then bogged down against the French defences. French attacks against Division from 19 to 27 February were repulsed but on 26 February, a French attack gained . On 5 March, the French captured a blockhouse and a German counter-attack by two regiments was defeated.