With the breaking of diplomatic relations between the USA and Germany a declaration of war was inevitable. Despite this it would be months before their contribution had a real impact on the war. Their troops were untrained and without equipment. General Pershing resisted all attempts to drag his men into the front line unprepared. He was determined to prevent the Americans being scattered as stiffening for the exhausted French and British armies. In Spring 1918 the Germans punched great gaps in the allied lines and Paris itself was once more threatened from the east. At Chateau Thierry on the Marne the US Marines fought one of their finest actions, first holding and then thrusting the Germans back at Belleau Wood. On 4 July alongside the Australians at Le Hamel they demonstrated that artillery, tanks, infantry and the air force, in combined operations, could advance without monumental casualties. Pershing got his chance to show his army in action under American command at St Mihiel in September. The salient was taken with minimum casualties, but soon the picture was to change. Against the massive obstacle of the Hindenburg Line and then in the Argonne the Americans encountered relentless German to the bravest best-planned attacks. Along the whole length of the Western Front the Allies pushed forward as the crumbling government in Berlin sought terms for an armistice. As the politicans talked, the soldiers died, until, on 11 November the guns fell silent.