The Preparations, Battle of the Somme
The British Fourth Army under General Rawlinson took over 23 miles of the front from the River Somme to the village of Fonquevillers in March 1916. The Job of mapping the trenches began. The Royal Flying Corps played a vital taking over 19,000 pictures during the battle for mapping purposes. Between April 1916 and March 1917 the Ordnance Survey sent over 7 million maps to France.
Surveys were also carried out for the artillery with regard to the positioning of the guns. A special survey was needed for the two railway guns which were used in the battle. The 9.2-inch gun was positioned on the branch line just south of Abert, while the 12-inch railway gun was to be positioned on the curve of the railway north of Dernancourt, 2 miles south west of Albert.
The 12-inch railway gun arrived at Dernancourt on the 24th of June and fired on Martinpuich the same day. By the 30th of June the gun had fired 81 12-inch shells. At zero hour on the 1st of July the gun fired on Bapaume at a range of 23,000 yards (13 miles) this drove the HQ of the German XIV Corps out of Bapaume. Of the 1,437 guns used by the fourth Army in the preliminary bombardment, Heavy artillery included the following howitzers, sixty-four, 8-inch, sixty, 9.2-inch, eleven, 12-inch, and six 15-inch. Some 1.6 million shells were fired before the battle started.
As well artillery there was also mining taking place along the front. The five Tunnelling Companies attached to the Forth Army had prepared mines, ready for the Battle of the Somme. The most northerly mine was the one on Hawthorn Ridge at Beaumont-Hamel, which was 75 feet deep, with a charge of 40,600 lbs of ammonal (18 ½ tons) Next in the line was Y sap which was at La Boisselle, the shaft was 70 feet deep with a charge of 40,000 lbs (18 tons) beneath the German lines. There were also two other mines close by each of 8,000 lbs at what was known as the Goly Hole.
The Mine known as Lochnager was started in December 1915, the gallery of the mine branched under its target “Schwaben Hohe” it was just south of La Boisselle, the galleries were each charged with 36,000 lbs and 24,000 lbs of ammonal, a total of nearly 27 ½ tons. Further down the line at Fricourt was what was known as the Triple Tambour, three mines charged with 9,000 lbs, 15,000 lbs, 25,000 lbs each. At Mametz a 2,000 lb mine was laid under what was known as the Bulgar Point. And at Kasino Point, Carnoy, a 5,000 lb mine was charged. There was also several small mines of 500 lbs laid.