At 7 in the morning on February 21, 1916, the ground in northern France began to shake. For the next 10 hours, some 1,200 German guns showered shells on a salient in French lines. The onslaught collapsed dugouts, obliterated trenches, severed communication wires, and drove men mad. The Battle of Verdun had begun.

Drawing from his book, Verdun: The Longest Battle of the Great War, Brandeis University historian Paul Jankowski looks back on what became one of history’s greatest and most demanding battlefield encounters – a 302-day nightmare that left an estimated 303,000 French and German soldiers dead and more than 400,000 wounded.