The story of the ill-fated Nivelle offensive of 1917, in which French commander Robert Nivelle galvanised 750,000 troops in a lightning attack on the German defences, only for the heavy losses inflicted on the French to lead to mutiny in the ranks. Meanwhile, the British found themselves under pressure at the third battle of Ypres, also known as Passchendaele, where the atrocious weather turned the battleground into a muddy hell. Richard Holmes also looks at the underground warfare waged during the battle.