The Polish–Soviet War (14 February 1919 – 18 October 1920) was fought by the Second Polish Republic, the Ukrainian People's Republic and the proto-Soviet Union (Soviet Russia and Soviet Ukraine) over a region comparable to today's westernmost Ukraine and parts of modern Belarus. Russia sought to cross Poland in order to stimulate a Europe-wide communist revolution under the Trotskyist slogan "to give water to red horses out of Wisła (Vistula) and Rhine".