google_ad_height = 60; April 9, 1917 - The British Army has one of its most productive days of the war as 3rd Army, supported by Canadian and Australian troops, makes rapid advances north of the Hindenburg Line at Arras and Vimy on the Western Front. Once again the British are called upon to launch an attack in support to a larger French offensive: the battles of the Chemin des Dames and the hills of Champagne. April 6, 1917: Facts & Myths About This Day. Mobilizing for War .