1. The Mines of Ypres

The British successfully used a mining technique known as 'clay kicking' to plant mines under German tunnels during three battles in Flanders. 500,000 soldiers were killed for 900 metres of gains.

3. Vauquois, Hill of Death

For three years, the Germans and French blow each other up with massive explosions, using a maze of underground galleries and tunnels. This story is told through the preserved diaries of Herman Hoppe, a German engineer who built many of the tunnels.

4. Col di Lana

Exploring trenches and tunnels and interviewing descendants of the Austrians and Italians who fought under and above the treacherous terrain of the Dolomite mountains.

5. The Secret of the Somme

An exploration of newly discovered fortresses, dugouts, and bunkers tells the story of the innovative German engineering that made defenses resistant to massive bombardments.