In October 1917, an invasion force of some 25,000 German soldiers, accompanied by a flotilla of 10 dreadnoughts, 350 other vessels, a half-dozen zeppelins, and 80 aircraft, attacked the Baltic islands of Dago, Osel, and Moon at the head of the Gulf of Riga. It proved to be the most successful amphibious operation of World War I. The three islands fell, the Gulf was opened to German warships and was now a threat to Russian naval bases in the Gulf of Finland, and 20,000 Russians were captured. The invasion proved to be the last major operation in the East. Although the invasion had achieved its objectives and placed the Germans in an excellent position for the resumption of warfare in the spring, within three weeks of the operation, the Bolsheviks took power in Russia (November 7, 1917) and Albion faded into obscurity as the war in the East came to a slow end.