Political map of South & Southwest Asia 16 August 1918 (Dunsterforce): The German (German Caucasus Expedition) and Ottoman occupation of Transcaucasia (Treaty of Batum) alarmed the British, who had by now replaced the Russians in northern Persia (North Persia Force). In response they sent an expedition under Lionel Dunsterville - and hence christened the Dunsterforce - to defend oil-rich Baku from the advancing Ottomans (Battle of Baku). However the Dunsterforce proved too small for the task and Baku had to be evacuated in September.