Army inspected the first position in the area of the 26th Reserve Division, who found that only in the area north of the Ancre, were there enough shell-proof concrete posts. On 12 May, the 2nd Guard Reserve Division was moved out of reserve, to defend Serre and Gommecourt, which reduced the frontage of the XIV Reserve Corps and its six divisions from between Maricourt and Serre, making the average divisional sector north of the Albert–Bapaume road wide, while the frontages south of the road were wide. By July 1916, the German front line from Thiepval to St Pierre Divion was obstructed by sixteen rows of barbed wire and the second line lay behind five rows. Shell-proof dug outs deep, could accommodate all of the trench garrison. Prelude 1 July Morning At the 36th (Ulster) Division troops formed up in no man's land and moved to within of the German front trench. The artillery and mortar bombardment lifted off the front trench at and the Irish advanced steadily, crossing the front trench with few losses but then the German counter-barrage fell on the rear of the first line and the support companies. As soon as the British guns stopped, machine-gun fire from Thiepval cemetery caught the third support battalion on the left flank. The foremost infantry pressed on, reached the B line at and took a large number of prisoners but German troops emerged from dugouts in the A line behind the 108th Brigade, whose moppers-up had been killed by machine-gun fire. The leading waves continued to advance and reached the C line and the corner of Redoubt at by when the supporting battalion survivors had occupied their objectives but cross-fire from German machine-guns then prevented movement forwards or backwards. Reserve Infantry Regiment 99 (RIR 99) of Reserve Infantry Brigade 52 (General von Auwäter), holding the line north of Thiepval, was broken through and the attackers rushed Redoubt. The garrison, a support company standing by to reinforce the front defences, was surprised and surrendered after brief resistance. The centre battalion of RIR 99 had been destroyed in the breakthrough and taken prisoner. An attack towards the Grandcourt Line ran into the British barrage and defensive fire from German guns on the north side of the Ancre near Miraumont and from and , either side of the Ancre. German machine-gunners in Grandcourt and (Beaucourt Redoubt) opened fire and the troops tried to