The German defences stretched back five miles from the front and included heavy concrete pillboxes housing machine-gun posts – the whole surrounded and protected by acres of barbed-wire entanglements. 

Despite some 1,738,000 shells being fired the eight-day bombardment scarcely made a dent on the German Second Army front lines because the enemy simply sheltered underground and re-emerged with machine-guns to mow down the advancing British troops. 

Furthermore, the barbed-wire was largely untouched – not least because a large percentage of sub-standard shells were used which never detonated – hence the large numbers of live shells still found in the area to this day.

If Haig was aware of this he didn’t share the knowledge and on the night before the battle started he wrote in his diary:

‘The weather report is favourable for tomorrow.  With God’s help, I feel hopeful.  The men are in splendid spirits several have said that they have never before been so instructed and informed of the nature of the operations before them.  The wire has never before been so well cut, nor the artillery preparation so thorough.  I have personally seen all the corps commanders and one and all are full of confidence.’ 
Haig’s Diary, 30 June 1916