Regard your masks as sacred, for gas causes as many casualties as artillery. -- German Anti-Gas Lecture
The 1917 campaign began on a positive note for the western Allies. Britain's newly constructed munitions factories were turning out materials in abundance and, along with purchases from neutrals such as the United States, the Entente would soon have a resource superiority on the western front. The coming year would also confirm the growing British edge in many new war technologies, including the tank, predicted artillery fire, and gas. Regarding morale, Haig believed that the battles of the Somme and Verdun had exposed a sense of fatigue in the German soldiers' commitment to the war, which, with further pounding, would widen and lead to a collapse of the German army. The withdrawal of the enemy to the prepared positions of the Hindenburg Line in late February to mid-March seemed to confirm that the battles of 1916 had indeed left the enemy weakened. The year would not end on such an optimistic note; the collapse of Russia threatened to redress Germany's numerical inferiority on the western front, the French army mutinied after the botched offensive along the Aisne, Italy suffered heavily in its futile efforts on the Isonzo (culminating with their disastrous defeat at Caporetto), and the British campaign of Passchendaele became associated with drowning mud and a distant leadership and staff. Even with these failures, however, 1917 proved to be the turning point in the war. Germany's gamble on unrestricted submarine warfare failed to starve Britain into submission and predictably forced the world's greatest industrial power into the Entente's camp. The entry of the United States assured eventual victory for the Allies, though the vital question remained: how to achieve decisive victory.
The British in 1917 made great strides in institutionalizing the technologies and tactics that would bring victory the following year. By the campaign season of 1917 most infantry platoons had a Lewis gun, which, combined with bombers, rifle grenades, and rifles, gave the units formidable firepower and maneuverability. 1 Of equal importance was the spreading of attack principles outlined in training manuals such