In Britain, an Offensive sub-committee of the Committee of Imperial Defence was appointed on 5 August and established a principle that command of the seas was to be ensured and that objectives were considered only if they could be attained with local forces and if the objective assisted the priority of maintaining British sea communications, as British army garrisons abroad were returned to Europe in an "Imperial Concentration". Attacks on German coaling stations and wireless stations were considered to be important to clear the seas of German commerce raiders. The objectives were at Luderitz Bay, Windhoek, Duala and Dar-es-Salaam in Africa and a German wireless station in Togoland, next to the British colony of Gold Coast in the Gulf of Guinea, which were considered vulnerable to attack by local or allied forces and in the Far East, which led to the Siege of Tsingtao.