On September 8, 1943, Italy changed sides in World War II, the king having already issued an order for Mussolini's arrest. Rescued by the Germans, he became the head of the Republic of Salò, a puppet regime over northern Italy. The defense of Italy and the suppression of its insurgent population were left to the Wehrmacht. After the loss of Sicily, they successfully defended the Gustaf Line south of the marshes, necessitating an Allied landing at Anzio and Nettuno in an effort to outflank the Germans. Malaria had returned to the Agro Pontino: quinine and other medicines were in short supply or withheld by the Germans, the food was bad, a shortage of metal prevented repair of the screens, and veterans returning from the Balkans brought back resistant strains of the disease.