Germany lost World War I because of the effectiveness of the Allied blockade of German ports and attrition from the length of the war.
The allies had blockaded all German ports preventing the importation of vital foodstuffs, medicines, and war supplies to Germany. Germany had in turn blockaded Great Britain, but the German blockade did not have the effect of the allied blockade. When needed supplies ran short, the German Reichstag set up the War Raw Materials Board to ration supplies. General von Hindenburg said Germany could win the war only
if all the treasures of our soil that agriculture and industry can produce are used exclusively for the conduct of war…All other considerations must come second
Children and expectant mothers were put on milk rations; housewives were encouraged to save the grease from their dishwater to use for lubricants; tin cans, bottles; even rotting leaves and animal manure were carefully saved. In a tragic error, the government ordered the slaughter of pigs to prevent their consuming the potato crop. However, the potato crop proved to be a bumper crop the surplus of which the pigs would have eaten. Instead the surplus potatoes rotted in the fields. People ate turnips which had previously been grown only as feed for livestock. Even so, many people starved.
The hardships ofthe war caused the people of Germany to rise in revolt. In the meantime, Allied forces had broken through German lines on the Western front. Workers struck and insisted on peace; and sailors in Kiel, a major port, mutinied. In the meantime, the Austro-Hungarian Empire collapsed. When dictatorial measures failed, the Reichstag sent a message to President Woodrow Wilson asking for peace terms. Wilson replied that he would only negotiate with the democratically elected government of the people of Germany. Revolts in Germany continued, and Wilhelm II was forced to abdicate and flee to Holland. At that point, the new German government asked for an armistice.