British plan of attack...(all trenches and objectives can be seen on the map)
The XIII Corps plan for the 30th Division was to capture Montauban on the first day; to the east of the village Nord Alley and Dublin Trench were to be captured to form a defensive flank to the French 39th Division at Dublin Redoubt. West of the village, the advance was to reach Montauban Alley and gain observation into Caterpillar Valley. The first objective was set at a German reserve line known as Dublin Trench and Pommiers Trench, about 1,000 yd (910 m) from the British front line. In the centre and on the left flank the advance was to continue to Montauban and the Montauban–Mametz Ridge and then the left flank was to advance a short distance, to improve the observation over German positions on the left. If the first phase succeeded and the attack further west captured Fricourt, XIII Corps was to wheel to the right by pivoting on Favière Wood and Dublin Redoubt. The third phase consisted of an eastwards advance via Bernafay and Trônes woods to the German second position from Falfemont Farm to Guillemont. When the plan was issued in mid-June, the 30th Division dug a new front line trench about 150–200 yd (140–180 m) closer to the German front line and six communication trenches between Maricourt on the right and Talus Boisé on the left, which was the boundary with the 18th Division.
The infantry advance was to be assisted by a heavy artillery barrage which was to fall successively on German defensive lines and a field artillery barrage which was to creep forward.[b] The short lifts of the creeping barrage, were to reach points registered beforehand, so that the advance of the barrage would fall on each length of trench obstructing the advance, each battery firing along a lane. Barrage lifts were determined by a time-table, based on the assumption that delays in the infantry advance, to wait for the barrage to move on were preferable to the risk of it moving too fast and allowing German troops time to emerge from shelters and engage the infantry with small-arms fire. The British infantry were to keep as close to the creeping barrage as possible and six artillery lifts were synchronised with the stages of the infantry advance. The 9th Division in corps reserve, was to move forward to sheltered localities about 2 mi (3.2 km) behind the old front line.
Two brigades of the 30th Division were to advance to the first objective, a line from Dublin Trench to Glatz Redoubt, in two stages by 8:28 a.m. The right-hand brigade was to stop at Casement Trench, which extended west from Dublin Redoubt and the brigade on the left was to reach Train Alley, 150 yd (140 m) west of Glatz Redoubt and to attack the redoubt. The third brigade was then to advance up Railway Valley and at 9:30 a.m. and pass through the leading brigades, to capture Montauban. On the left flank, the 18th Division was to advance parallel with the 30th Division. As the final objectives were reached, strong points were to be built by a Field Company section of the Royal Engineers (RE) and detachments from two pioneer battalions, which were attached to each brigade. Parties of infantry and machine-guns were to move forward to La Briqueterie, which had a chimney used by the Germans as an observation point and other areas useful for British artillery observation. Several batteries of field guns were to move forward to command ground between the new front line and the German second position and a box-barrage was to be fired around Montauban to deter a German counter-attack...