[3] The Somme was to be the first mass offensive mounted by the British Expeditionary Force (BEF) and the first battle to involve a large number of New Army divisions, many composed of Pals battalions that had formed after Kitchener's call for volunteers in August 1914.

The 55th (West Lancashire) and 56th (1/1st London) divisions were reassembled, a battalion of the Newfoundland Regiment and the South African Brigade joined in April, followed by a contingent of the Bermuda Volunteer Rifle Corps in July.

Battle would now be methodical until the power of resistance of the defender was broken by "moral, material and physical degradation", while the attacker retained the ability to continue the offensive; a breakthrough was unlikely but not ruled out.

There had been a debate about the merits of a short hurricane bombardment but there were insufficient guns quickly to destroy German field defences and be certain that barbed wire was cut, given the dependence of the artillery on air observation and the uncertain weather.

[19] Shrapnel shells were virtually useless against entrenched positions and required accurate fuze settings to cut wire; very little high-explosive ammunition had been manufactured for field artillery.

The 1st, 2nd (Indian) and 3rd Cavalry divisions were to assemble by zero hour 5 mi (8.0 km) west of Albert around Buire, Bresle, Bonny and La Neuville, ready to move forward or remain and then return to billets behind Amiens depending on events.

[24] A BEF manual published on 8 May 1916 (SS 109, Training of Divisions For Offensive Action), described successions of lines to add driving power to the attack, to reach the objective with the capacity to consolidate the captured ground against counter-attack.

In the 37th Division area, 91,420 man-hours were needed to dig 3.7 mi (6 km) of trenches, jumping-off points, command-posts, dug-outs, machine-gun emplacements and ammunition stores, for wiring and for maintenance.

In late June, the British part of the Somme plan was amended, rapidly to capture Bapaume and envelop the German defences northwards to Arras, rather than southwards to Péronne.

Haig had exhaustive negotiations with Joffre and rejected the concept in favour of the capture of the ridge north of Péronne to assist a French crossing of the Somme further south.

Diversion of French divisions to Verdun and the assumption by the British of the main role in the offensive, led to revisions of the plan towards an ambitious attempt at strategic attrition, through a breakthrough and a battle of manoeuvre with distant objectives.

On 19 April, Rawlinson wrote that an attempt to reach the German second line on the first day was doubtful, an extension of the attack in the south on Montauban required another division and the inclusion of Gommecourt to the north, was beyond the resources of the Fourth Army.

Rawlinson also wrote that long bombardment was dependent on the French, the availability of ammunition and the endurance of gun-crews; the exploitation of a successful attack would need a substantial number of fresh divisions.

[46] On 28 June, the Fourth Army headquarters instructed that if the Germans collapsed, the closest infantry would exploit without waiting for cavalry; the 19th (Western) and 49th (West Riding) divisions (in local reserve) would be committed along the Albert–Bapaume road and parallel to it to the north.

[47] Haig had formulated a plan in which success of any magnitude could be exploited but Rawlinson had a much more modest intention of small advances onto high ground and pauses to consolidate, to repulse German counter-attacks, which led to an "unhappy compromise".

Railways, roads and waterways connected the battlefront to the Ruhr, the source of material for minierte Stollen, dug-outs 20–30 ft (6.1–9.1 m) underground, big enough for 25 men each, excavated every 50 yd (46 m).

More railway activity, fresh digging and camp extensions around Albert opposite the 2nd Army was seen by German air observers on 9 and 11 June; spies reported an imminent offensive.

At Verdun, on 24 June, Crown Prince Wilhelm was ordered to conserve troops, ammunition and equipment and further restrictions were imposed on 1 July when two divisions were taken under OHL command.

In the chaos, alarmist reports were received that Bernafay and Trônes woods had been captured and before noon, every available man, including clerks and cooks was ordered forward to the second position.

The garrison of Thiepval emerged from the shelters and cellars of the village before the British arrived and cut them down with small-arms fire, leaving a "wall of dead" in front of the position.

[79] The preliminary artillery bombardment, which included support from French batteries firing gas-shell and a smoke screen from trench mortars, was more successful than on other parts of the front north of the Albert–Bapaume road.

In the confusion, few of the German troops were able to assemble; the counter-attack began piecemeal and was repulsed several times, until a bombardment and another attack by two fresh battalions at about 10:00 p.m., forced the Irish out of the redoubt.

Small groups of the Accrington Pals and the Sheffield City Battalion managed to cross no man's land and reach Serre and a party advanced 1.25 mi (2.01 km) to Pendant Copse, before being cut off and killed or captured.

A German barrage descended on no man's land, which made it impossible for reinforcements to move forward or for a trench to be dug as a defensive flank to the south and the survivors were forced to withdraw after dark.

The bombardment on 30 June repeated the pattern of the earlier days, by when, much of the German surface defences had been swept away, look-out shelters and observation posts were in ruins and many communication trenches had disappeared.

Prior and Wilson ascribed the origin of this narrative to John Buchan in The Battle of the Somme (1917) in which the bravery of soldiers is extolled, rather than faulty infantry tactics being criticised.

Prior and Wilson traced the narrative through the writing of B. H. Liddell Hart, J. E. Edmonds the official historian, C. R. M. F. Cruttwell, Martin Middlebrook, Correlli Barnett and Paul Kennedy.

Of 80 battalions in the initial attack, 53 crept into no man's land, ten rushed from the British front trench and twelve advanced at a steady pace behind a creeping barrage.

Terrain in the south, Anglo-French air superiority and closer objectives, tended to concentrate Allied artillery-fire, which was better-observed and more accurate than on the hillier ground to the north.

[128] In the evening of 1 July, Haig wrote in his diary, North of the Ancre, VIII Division (sic) said they began well but as the day progressed, their troops were forced back into the German front line, except two battalions which occupied Serre village and were, it is said, cut off.