The Allied 1917 Spring Offensive masterminded by French general Robert Nivelle was supposed to end the stalemate on the Western Front and bring a decisive breakthrough. But the German Army also knew they couldn't win the war on the offensive and thus prepared a new type of defensive system: The Hindenburg Line and it would be tested in the Battles of Arras (Vimy Ridge, Bullecourt) and Chemins des Dames (Aisne).
