Armistice between Russia and the Central Powers

On 15 December [O.S. 2 December] 1917, an armistice was signed between the Russian Republic led by the Bolsheviks on the one side, and the Austro-Hungarian Empire, the Kingdom of Bulgaria, the German Empire and the Ottoman Empire—the Central Powers—on the other. The armistice took effect two days later, on 17 December [O.S. 4 December].

Source: Wikipedia — Armistice between Russia and the Central Powers (CC BY-SA 4.0)