World War I, also known in its time as the "Great War" or the "War to End all Wars", was an unprecedented holocaust in terms of its sheer scale. Fought by men who hailed from all corners of the globe, it saw millions of soldiers do battle in brutal assaults of attrition which dragged on for months with little to no respite. Tens of millions of artillery shells and untold hundreds of millions of rifle and machine gun bullets were fired in a conflict that demonstrated man's capacity to kill each other on a heretofore unprecedented scale, and as always, such a war brought about technological innovation at a rate that made the boom of the Industrial Revolution seem stagnant.

The enduring image of World War I is of men stuck in muddy trenches, and of vast armies deadlocked in a fight neither could win. It was a war of barbed wire, poison gas, and horrific losses as officers led their troops on mass charges across No Man's Land and into a hail of bullets. While these impressions are all too true, they hide the fact that trench warfare was dynamic and constantly evolving throughout the war as all armies struggled to find a way to break through the opposing lines.

There was another war going on beneath the trenches, a war of tunnels and mines fought by men who didn't see sunlight for days at a time and who lived in constant fear of cave-ins and enemy detection. These men, who had mostly been miners in civilian life, lived a twilight existence, working long hours in silence and near darkness while great battles raged overhead. They suffered from fatigue, stress, and the knowledge that they could be killed at any time by an unseen enemy. Despite this, they persevered, and the mines they laid under enemy trench systems turned the tide of at least one major battle.