PBS - Nova: Secret Tunnel Warfare (2016) 720p HDTV x264-CURIOSITY

During World War I, the Allies and Germans repeatedly struggled to break the hideous stalemate of trench warfare. In the winter of 1916, Allied engineers devised a massive surprise attack on the German army.. NOVA follows bomb disposal experts as they clear topsoil packed with shrapnel and unexploded shells and probe one tunnel system connected to what is probably the world's largest unexploded bomb--a mine consisting of 22 tons of explosives that was flooded by German engineers before the attack. "Secret Tunnel Warfare" opens a unique window on the frenzy of Allied mining activity that led up to the attack, and its bitter aftermath.