Trench warfare
Trench warfare prevailed on the Western Front from late 1914 until the Germans launched their Spring Offensive on 21 March 1918. After the buildup of forces in 1915, the Western Front became a stalemated struggle between equals, to be decided by attrition. Frontal assaults, and their associated casualties, became inevitable because the continuous trench lines had no open flanks. Casualties of the defenders matched those of the attackers, as vast reserves were expended in costly counter-attacks or exposed to the attacker's massed artillery. There were periods in which rigid trench warfare broke down, such as during the Battle of the Somme, but the lines never moved very far. The war would be won by the side that was able to commit the last reserves to the Western Front.
32nd Infantry Division (United States)
Captain Alien L. Briggs returned to Camp MacArthur to assist with training. He had been an Aide-de-camp to General Parker and had been in Europe when the war broke out in 1914. He had observed the training methods used in military schools in France. As training intensified in preparation for leaving for France, five French and four British officers, along with several non-commissioned officers, joined the division as instructors. A trench system was built outside the camp in which the division practiced the techniques of trench warfare. There was a continual shortage of equipment that hampered training in the artillery and machine gun battalions. Additional training for junior and non-commissioned officers was implemented, and General Haan offered additional daily instruction to the brigade, regimental and battalion commanders.