Lochnagar Crater, just to your left, the front is directly in front of you, as in eth British lines, The German lines are beneath your feet as indeed are a lot of soldiers.
This was a mine, laid by the British, under the German lines, A lot of ammonal, a lot of bangs, a lot of dead and disorientated enemy. Not disorientated enough to leave the position they cut the 34th Division down in swathes. this area was hotly contested for a fair while in July 1916. Eventually the British and Commonwealth troops took it.
I read a harrowing passage recently about the sheer number of bodies from both sides of the line who were slid into the bottom of the crater, their remains swallowed by the fractured chalk and marl slipping down the side, It remains the last resting place of a lot of boys.
It's all a bit Golgotha really what with the huge wooden cross.