At Messines in Belgium, bomb disposal specialists work alongside archaeologists on WWIs biggest archaeological dig. During the First World War this was one of the killing fields of the Western Front and 100 years later the ground is still littered with unexploded shells, grenades and ammunition. Held by the British in 1914, Messines was captured by German troops, including a young Adolf Hitler, and for nearly three years the two opponents faced each other in trenches, which the archaeologists uncover. What are revealed are trenches, which have seen the results of some very heavy fighting.

By 1917 German troops had been facing the British in trenches at Messines for almost three years. Archaeologists discover German tunnels - evidence of an underground war. A camera is lowered down a flooded German mineshaft to looking for remnants of this subterranean battleground because on one night here 19 bombs were detonated beneath German strongpoints killing 10,000 German soldiers in seconds and creating the biggest explosion that the world had ever seen.