Note: The Polish Corridor was the narrow strip of land that gave Poland access to the Baltic Sea by provision of the Treaty of Versailles in 1919. It was located along the lower course of the Vistula river, including western Prussia and most of the province of Posen. It separated eastern Prussia from the main body of Germany and caused great resentment among Germans. Nazi dictator Adolf Hitler used it as a pretext for the invasion of Poland in 1939, thus beginning World War II. Today the Corridor's area is part of Poland.