In 1943, the Italian government under General Bagdolio surrendered unconditionally to the Allies. On October 13, 1943, this government, which controlled those portions of Italy occupied by the Allies, declared war on Germany. The next day, the Bagdolio government was accepted as a co-belligerent.
The Italian Co-Belligerent Air Force (as it came to be known by the Allies) was then reequipped so that it could fight against the Germans. The USAAF Fifteenth Air Force turned over 75 P-39Qs from the 332nd Fighter Group and 74 P-39Ns to the Italian Co-Belligerent Air Force. The 350th FG had inherited the 332nd FG's P-39s when the latter group transitioned to more modern fighters, and they gave their P-39s to the Italians when they themselves transitioned to the P-47 Thuderbolt. Personnel from the 345th FS helped the Italians familiarize themselves with the P-39s.
The P-39s were employed in training at Campo Vesuvio since Jun 20, 1944 by 12o Gruppo, followed in July by 9o and 10 Gruppi (the three Gruppi constitutiing the 4o Stormo Caccia) and supplied operationally to 4o Stormo in Lecce-Galatina by mid October.
The Italians flew missions against German forces over Yugoslavia, flying escort duties, dive bombing and strafing attacks. After the end of the war, the P-39s remained operational with 4o Stormo until they were replaced in 1946 by P-38L Lightinings and later by P-51Ds. Surviving P-39s were then assigned to the Flying School of Lecce, being later scrapped. The Italians flew their P-39s until 1950, but there was still one being used as a burning target by a fireman's school as late as the early 1960s.