German reserves in France on the road to Albert, east of Amiens, to keep Ludendorff's Spring Offensive from faltering. The 1918 Spring Offensive was a series of German attacks along the Western Front during World War I, beginning on March 21, 1918, which marked the deepest advances by either side since 1914. The Germans knew that their only chance of victory was to defeat the Allies before the overwhelming human and materiel resources of the United States could be deployed. The Germans were unable to move supplies and reinforcements fast enough to maintain their advance. By late April 1918, the danger of a German breakthrough had passed.