The 152nd Infantry Regiment arrived to reinforce the ; after a four-hour artillery preparation, the infantry and captured two trench lines and took 250 prisoners but failed to penetrate new German trench lines close to the peak. The French attacked again on 17 and from 23 March - 6 April; on 26 March, after a preparatory bombardment, the 152nd Regiment captured the summit of Hartmannswillerkopf in ten minutes, taking 400 prisoners and finding that the ground had been stripped of trees by the artillery exchanges. The Germans suspended the offensive at Wattwiller and Steinbach to concentrate all reserves in the Hartmannswillerkopf area but on 17 March, the German army chief of staff, General Erich von Falkenhayn, ordered offensive operations in Alsace to cease. The French success had enabled artillery-observers to direct their guns onto the Colmar-Mulhouse railway and local German attacks on 25 April took back the peak; the French recaptured it the next day the 152nd Regiment suffering 825 casualties.