Fighting in Southern Europe did not resume until Axis forces were defeated in North Africa. Following the Axis defeat in Africa, Allied forces invaded Italy and during a prolonged campaign fought their way north through Italy. The invasion of Italy resulted in the nation switching sides to the Allies and the ousting of Mussolini. But, in spite of this coup, Fascists and occupying German forces retained possession of the northern half of Italy. In the northern part of Italy, the occupying Germans installed Mussolini as the head of the new fascist republican government, the Italian Social Republic or RSI to show that the Axis forces were still in power there and a force to be dealt with. But Mussolini and his Fascists were now puppet rulers under their German patrons.