The Polish Navy was a small fleet of destroyers, submarines and smaller support vessels. Most Polish surface units followed Operation Peking, leaving Polish ports on 20 August and escaping by way of the North Sea to join with the British Royal Navy. Submarine forces participated in Operation Worek, with the goal of engaging and damaging German shipping in the Baltic Sea, but they had much less success. In addition, many merchant marine ships joined the British merchant fleet and took part in wartime convoys.