1917 - The Russian Revolution starts, the front crumbles in the east.
1918 - The treaty of Brest-Litovsk end hostilities in the east. The Germans launch the Spring Offensive in the west and reach Paris. The French army is plagued by mutinies, and with revolution on their doorstep, the French government rushes to get a favorable armistice. The Germans occupy everything to the east of the Meuse, including the riverbanks to the west of the Meuse. All German colonies are awarded to France, Britain and Japan. The war has officially ended.
1919 - The treaty of Berlin finalises the borders in the east with the Soviet Union. Roughly all territory gained by Prussia in the Third partition of Poland is annexed to Prussia as the provinces of Lodz and Southeast Prussia. The United Baltic Duchy is made a member of the German Empire. Lithuania, Finland and Ukraine are established as independent states.
1920 - All French and Belgian territory east of the Meuse is annexed to Germany in the final peace treaty with France. The Belgian territories and a small part of former French territory is annexed to Prussia as the province of the Ardennes, the rest goes to the Imperial Land of Alsace-Lorraine.
1923 - All German troops leave French and Belgian territory. Belgium elects anti-German parties.
1924 - Civil unrest in Belgium. The German army moves in. The rest of Belgium is annexed to Prussia as the province of Flanders. The Belgian Congo is split between France and Britain.
Due to no unrestricted submarine warfare and subsequently no American entry in the war, the Central Powers stand victorious. Just a quick scenario for Map of the Fortnight on AH.com.