Well, actually, at the armistice ending the fighting in the Great War, was signed on November 11, 1918. However, the very effective naval blockade of Germany and the Austrian cohorts begun in the early days of the War, was continued until the signing of the Treaty of Versailles in June of 1919. The blockade was conducted by the Allies and particularly by the British navy, the most powerful navy in the world at the time. (By September 1916, the British fleet was single handedly intercepting an average of 135 merchant ships every week.)
Churchill referenced the continuance of the blockade in a speech before the House of Commons in March of 1919 and he especially remarked about the starvation in Germany.
The tremedous losses sufered by all sides, but especially the Western Alliance of France, England and the Commonweatlh and to a lesser extent, the United States created great hatred against German nation and people. The seeds of WWII found fertile soil from the actions of all involved, but the tremedous reparations demanded of Germany in the Treaty of Versailles was aprimary contributor.
Additionally, an already weakened populace in Germany suffered along with most other European and United Kingdom countries from the influenza pandemic of 1918-1919 that killed nearly 20 million people worldwide.
And, as dot.hawkes references, Failure of the potato crop in 1916 led to turnips replacing potatoes as the principal staple, and the particularly severe winter of 1916-17 was dubbed the 'turnip-winter'.