The German high command recognized that a window had opened in the spring of 1918. Revolution had forced Russia to withdraw from the war allowing Germany to transfer troops from the eastern to the western front.  U-boat attacks were taking a devastating toll on Allied shipping.  The French army’s morale was low and the French public was clamoring for peace.

But how long Germany’s window would remain open was unclear.  The Allied naval blockade was producing hardship in the army and the general public.  German support for the war would not last forever.  Even more unclear was the significance of the United States’ declaration of war.  American troops had begun to arrive en masse by the spring.  But how they would be used and how well they would fight was unknown.

Therefore, General Erich Ludendorff, head of the German army, decided to seize the moment and launch a major offensive in the spring of 1918.  He believed that the British lines in the north of France were vulnerable and that if he were able to drive a wedge between the British and French armies, the war could be won. He attacked the British along a forty-mile front near Arras on 21 March.  

The German attack went according to plan. An intensive artillery attack softened the British lines and then divisions from three German armies marched through the heavy morning fog toward the British.  Visibility was miserable—even worse after German gas attacks forced the soldiers to don gas masks.  Yet while both sides were handicapped, the static British troops, somewhat contrary to logic, seemed more disoriented than the forward-marching Germans.  By the time the fog lifted, German troops had broken through the British lines.  

The German attack proceeded without a hitch for ten days.  German troops advanced forty miles until they supply outran their supply lines and had to stop.  During the lull French re-enforcements arrived on the scene, and the German’s opportunity had passed.  

Ludendorff, therefore, decided to shift the point of his attack further north, along the French-Belgium border near Ypres.  This battle, launched 9 April followed an almost identical script. An artillery barrage preceded an overpowering wave of German ground troops.  The British were forced to retreat until the combination of over-extended supply lines and French re-enforcements brought the German advance to a halt.

At this point, Ludendorff changed his strategy.  Now believing that the British would hang on until France lost the ability to re-force its ally, Ludendorff moved south to attack the French lines along the Chemin des Dames.  An attack here would force the French to stay put and a subsequent German attack to the north would find the British without French help. 

Ludendorff’s plan started out brilliantly.  Knowing that the Germans’ priority was to the north, and believing that any movement to the south was just a diversion, the French were caught by complete surprise by the German attack on 27 May.  German artillery ripped holes in the densely-packed French troops lining the ridge overlooking the Aillette River.  Advancing German troops found the shattered French troops in total disarray and stormed through the lines with little resistance.  By 5 June they had reached the Marne. In just one week, the Germans had advanced forty miles and stood only another forty from Paris.

Here once again, the speed of their advance began to cause problems for the Germans. Supply and communications lines were badly overextended.  Once again, Allied re-enforcements began to plug some of the holes in the French lines.  But here for the first time, American troops made a significant contribution.  At Château-Thierry and Belleau Wood, army and marine divisions proved decisive in stemming the German advance. 

The action at Château-Thierry was relatively brief.  American forces met with French allies at the Marne on 3 June and forced the Germans back across the river.  At Belleau Wood, however, the battle raged for three weeks.  In the first phase, the Germans assumed the offensive, trying to advance on 3 June against the US Marines manning shallow trenches.  The French commander had urged the Americans to fall back, but dramatically, according to legend, the Marine commander responded, “Retreat! Hell, we just got here.” Their dogged defense forced the Germans to retreat and then settle into a defensive position of their own. Now it was the Americans’ turn to take the offensive.  Launching six major assaults over the next twenty days, the Marines courageously—or recklessly—charged into the face of the German machine guns. “Come on, you sons of bitches,” urged one gunnery sergeant, “do you want to live forever?"  Almost 2000 Americans died in these attacks.  But by 26 June, they had taken Belleau Wood and forced the Germans into flight.