March 1918.
After achieving a decisive victory in the East, following the collapse of Russia and the signature of the Treaty of Brest-Litovsk with the new Bolshevik leadership, General Erich Ludendorff argued that a decisive offensive in the West was possible in 1918, and would bring victory to Germany by splitting the Western coalition (but result in utter defeat if it failed).
In a decision that historians have argued was short-sighted and lacking in strategic vision, Ludendorff opted to concentrate his spring offensives on the sector splitting British forces to the North and French forces to the South (Kaiserschlact [Emperor's Battle], also called Operation Michael -- named after the patron saint of Germany --, was the first of a series of offensives planned for the spring of 1918 targeting the neighboring British 5th and French 6th armies).
History has shown that this strategic plan was flawed, because even though the front was decisively broken, and British forces were in full retreat with German advances limited mainly by their capabilities to move up supplies, it actually had the effect of strengthening the alliance by forcing the British to accept French command (at the height of the offensive modeled in this scenario) and prompting the U.S. to speed up reinforcements (which proved decisive in war-winning Allied offensives executed later in the year).
Numerous post-war analyses concluded that a strategic offensive targeted at Flanders and the Channel ports would probably have been successful, and achieved a more decisive military effect, but not the elusive political impact that was the objective of Operation Michael.
