Siege of Saïo the Italian dictator, Benito Mussolini, proclaimed the colony of "Africa Orientale Italiana" (AOI, Italian East Africa), formed from Ethiopia (after the Italian victory in the Second Italo-Ethiopian War, fought 3 October 1935 – May 1936) and the existing Italian possessions of Italian Eritrea and Italian Somaliland. On 10 June 1940, Mussolini declared war on Britain and France, which made Italian military forces in Libya a threat to Egypt and those in Italian East Africa a danger to the British and French colonies in East Africa. Italian belligerence also closed the Mediterranean to Allied merchant ships and endangered British supply routes
Italian guerrilla war in Ethiopia to accept an Italian protectorate with these conditions: In the summer of 1942, the most successful units were those led by Colonel Calderari in Somalia, Colonel Di Marco in the Ogaden, Colonel Ruglio amongst the Danakil and "Blackshirt centurion" De Varda in Ethiopia. Their ambushes forced the British to dispatch troops, with airplanes and tanks, from Kenya and Sudan to the guerrilla-ridden territories of the former Italian East Africa. That summer, the British decided to put most of the Italian population of coastal Somalia into concentration camps, in order to avoid their possible contact with Japanese submarines. In October 1942,