Germany agreed a ceasefire on 11th November 1918 (known as the armistice). There were 3 main reasons why the war came to an end and Germany lost:
1) The success of the Allied blockades
From the start of the war, the allies used their navies to block Germany's port and prevent foodstuffs and other vital supplies (like war materials) from entering Germany. Britain had the largest naval in the world so the blockades were very effective. Thousands of German civilians died as a result.
The Germans also tried to block Britain's ports but they were less successful as their navy was inferior to the British. They did have one major advantage though - the U Boat. The U Boat was a German submarine which was much feared as it could attack ships without detection. The German U Boats sunk thoughts of merchant ships and eventually started attacking passenger ships.
The German blockades were unsuccessful because Britain introduced a convoy system where merchant ships travelled in groups protected by warships and this kept Britain's supplies coming in.
Germany made one fatal error - it sunk the passenger ship, the Lusitania killing 100 American citizens. This…