But soon Britain struck back at the end of that year. In December 1940, British and Commonwealth forces launched Operation Compass which, by February 1941, ended in the conquering of all of Cyrenaica and the complete destruction of a large Italian army. In January 1941, other British and Commonwealth forces launched an invasion of Italian East Africa. By November of that year, at the conclusion of the East African Campaign, the last organized Italian troops surrendered with military honors in Gondar while some Italian officers started a guerrilla war, mainly in Ethiopia and Eritrea.