The participation of the Regia Aeronautica in the Battle of Britain may be considered a purely political, instead of military, decision. At the closing of the hostilities with France in the summer of 1940, Mussolini decided to create an Expeditionary Corps to support the Luftwaffe on raids across Channel, thus giving the Italian armed forces a representation in the Battle of Britain.
Consequently on 10 September 1940 the Corpo Aereo Italiano (CAI) was formed, comprising bomber and fighter units that were based in Belgium. General SA Rino Corso Fougier was selected to command the CAI. Personnel amounted to 89 officer and 69 NCO pilots, 81 mechanics and 171 other personnel with diverse tasks.
Considering the technical characteristics of the Italian aircraft, especially the fighters which once over England had only 10 minutes loitering capability, a special operations area was arranged with the German command, reserved for the Italian aircraft. This area was limited by the 53rd parallel to the north, the 1°W meridian to the west and the Thames to the south. Logistics were established to make the units operational: the Germans would furnish installations and equipment to be managed by the Italians. German efficiency, as usual, was remarkable – Italian personnel arriving on the Belgian bases found good installations complete with camouflaged dispersal areas. All other logistic material was dispatched from Italy by train or transport aircraft, the whole transfer being completed by 24 September.
Very soon the deficiencies of the Italian equipment became evident. The aircraft lacked any sort of armour and the crews were not used to the demanding weather conditions over the Channel, which sometimes rendered operations extremely difficult. These deficiencies were compounded by the lack of navigation and radio communication equipment and the language difference with the Germans.
On the night of 24 October a formation of Fiat BR20Ms went out on their first bombing mission attacking the port installations of Harwich and Felixstowe in unfavorable weather. Twelve bombers from 13° Stormo and four from 43° Stormo were detailed for this mission, which began in the worse manner when MM21928 of 5° Squadriglia crashed just after takeoff from Melsbroeck killing its whole crew. Two other bombers turned back due to mechanical failures and the remaining aircraft managed to drop their load of 100kg bombs on the target despite intense anti-aircraft fire that damaged one machine. The return flight was heavily hampered by the adverse weather resulting in the loss of MM21895 and MM22601 which, following radio failures, both got lost forcing their crews to bale out.
After this first mission it was decided to operate on day bombing missions only, such as the attack on the port installations at Ramsgate on 29 October by 15 bombers of 43° Stormo escorted by fighters of 56° Stormo. Two aircraft turned back with mechanical failures and the remainder dropped 72 100kg and nine 250kg bombs on the target. The flak was particularly heavy and several of the Italian aircraft were hit, one of which failed to return with its crew baling out over Belgium.
The next mission was on 1 November, the day after the Battle had officially ended. Sporadic sorties continued until 23 December 1940, when the order came for the remaining CAI aircraft still in Belgium to return to Italy by January. The last bombing mission was carried out by four BR20Ms of 13° Stormo attacking the port of Harwich on 2 January. Personnel losses amounted to 34 killed and 22 wounded, of which 14 were killed and nine wounded in aerial combat.
Though most of the CAI returned home, two Fiat G50 units from 20° Gruppo remained in Belgium operating in an autonomous way under control of the Luftwaffe until April 1941, engaged in patrols and interception duties. It was initially considered to re-equip the Italians with Bf 109Fs, but after an initial training period it was decided to send those remaining back to Italy too.
The whole operational activity in the three months that the CAI was based in Belgium amounted to 144 bombing sorties, 1640 fighter sorties and five reconnaissance missions. Losses amounted to 11 bombers and 25 fighters, of which 26 were due to accidents or mechanical failure. It is remarkable that the Fiat G50 monoplane, while of a more modern design than the Fiat CR42, was engaged in the operations in a very limited way, mainly due to its short range. Therefore, very often the BR20 escort duties fell to the CR42 biplanes.