Читайте.достаточно подробно изложеноhttps://ru.wikipedia.org/wiki/%D0%9F%D1%80%D0%B5%D1%82%D0%B5%D0%BD%D0%B4%D0%B5%D0%BD%D1%82%D1%8B_%D0%BD%D0%B0_%D1%80%D0%BE%D1%81%D1%81%D0%B8%D0%B9%D1%81%D0%BA%D0%B8%D0%B9_%D0%BF%D1%80%D0%B5%D1%81%D1%82%D0%BE%D0%BB_%D0%BF%D0%BE%D1%81%D0%BB%D0%B5_1917_%D0%B3%D0%BE%D0%B4%D0%B0