In the early morning hours of May 27, 1918, the German army begins the Third Battle of the Aisne with an attack on Allied positions at the Chemin des Dames ridge, in the Aisne River region of France.
By mid-May 1918, General Erich Ludendorff, mastermind of the ambitious German offensive—known as the Kaiserschlacht, or the "kaiser's battle"—launched that spring, was determined to reclaim Chemin des Dames from the French with a forceful, concentrated surprise attack on the strategically crucial ridge. There had been two previous battles in the Aisne region, in 1914 and 1917, but both had been offensives by the Allies—predominately the French—against the Germans; the second was part of the failed Nivelle Offensive, named for Robert Nivelle, the French commander in chief who was summarily replaced in the wake of the offensive's disastrous outcome. Nivelle's successor, Phillipe Petain, was aware of the likelihood of a German attack at the Chemin des Dames in 1918, but he failed to anticipate its strength and scale.
In the early morning hours of May 27, 4,000 German guns opened fire on a 24-mile-long stretch of the Allied lines, beginning the Third Battle of the Aisne. The Germans advanced 12 miles deep through the French sector of the lines near Chemin des Dames, demolishing four entire French divisions. Four more French and four British divisions fell between the towns of Soissons and Reims, as the Germans reached the Aisne in less than six hours. By the end of the day, Ludendorff's men had driven a wedge 40 miles wide and 15 miles deep through the Allied lines.
Earlier that month, the political and military chiefs of France and Britain had invested supreme control over their joint military strategy on the Western Front to Ferdinand Foch, chief of the French general staff. Foch's control over the other commanders in chief proved relatively limited in this instance, however, as he was unable to force Britain's Douglas Haig to transfer more than five British divisions to relieve French troops. The Germans were not as successful elsewhere on the Western Front, however, as an Allied force including some 4,000 Americans scored a major victory at Cantigny, on the Somme River, on May 28. Even as the German spring offensive continued in force, the Allied defense was stiffening, and as the summer of 1918 began, Petain, Foch and the rest of the Allied commanders began to shift their focus to counterattacks, knowing the outcome of World War I hung in the balance.