World War I is generally considered to have ended on 11 November 1918, when an armistice between Germany and the Allied powers came into effect at the 11th hour of the 11th day of the 11th month.

However, if you look at the war in a more formal/legal sense, several key dates matter.

  • The armistice (ceasefire) on 11 November 1918 stopped the fighting on the Western Front.
  • The Treaty of Versailles , signed on 28 June 1919 and in force from 10 January 1920, officially ended the state of war between Germany and the Allies.
  • Some historians argue the wider consequences and related conflicts (like the Greco‑Turkish War and others) mean the “real” end of the First World War only came with later settlements such as the Treaty of Lausanne in 1923.

So, for the question “when did WW1 end,” the simple, widely accepted answer is: 11 November 1918 , with the armistice that silenced the guns.