Mario Pinna served in the 23^o Gruppo during the whole war but he also served in the Gruppo's three Squadriglias respectively, the 70^a, 75^a and 74^a.

In June 1940 he served in the 74^a Squadriglia, 23^o Gruppo, 3^o Stormo. This unit was equipped with Fiat CR.42s.

When the war started on 10 June 1940 the 3^o Stormo was sent to the French border to take part in the attacks on southern France.

Pinna took part in the big attack on French airfields on 15 June.

In July 1940 the 23^o Gruppo moved to Sicily and took part in the attacks on Malta.
On 9 July the 23^o Gruppo became Autonomo and the first escort missions over Malta was flown on 12 July. At this time Pinna served in the 70^a Squadriglia, which was based at Pantelleria.

Shortly after 09:00 on 16 July, a dozen CR.42s of 23^o Gruppo appeared over Malta on a reconnaissance mission. Flight Lieutenant Peter Gardner Keeble in a Hurricane Mk.I (P2623) and Flight Lieutenant George Burges in a Gladiator had been scrambled, and dived on this formation. Keeble attacking one CR.42, but being attacked himself by two more flown by Tenente Pinna and Sottotenente Oscar Abello (both from 70^a Squadriglia). After a long chase Keeble was hit and his aircraft dived out of control towards the south-east of the Island where it hit the ground near Wied il-Ghajn and blew up. It was immediately followed by a CR.42 flown by 24-year-old Tenente Mario Benedetti (MM4368) of the 74^a Squadriglia, which crashed within 100 yards of the Hurricane. Keeble was killed outright but Benedetti survived the initial impact of his crash, but died soon afterwards at the civilian hospital at Vincenzo Bugeja without regaining conscious.
Burges made no claim on this occasion, and subsequently it was claimed that Benedetti’s aircraft was brought down with LMG fire by C Company headquarters, 1st Battalion The Dorsetshire Regiment. It is also possible Benedetti’s aircraft was the one attacked by Keeble.
Sergente Maggiore Renzo Bocconi claimed a second Hurricane, but this was not allowed by the 2^a Squadra intelligence staff.
Keeble was the first of Malta's fighter pilots to lose his life in the defence of the island.

In August 23^o Gruppo Autonomo CT moved to Libya to take part in the operations there.

Capitano Guido Bobba was killed in action on 26 December. He was replaced as CO of the 74^a Squadriglia by Tenente Pinna.
Pinna was also promoted to Capitano during this period.

At 12:45 on 5 January 1941 eight SM.79s of 41^o Stormo BT and 17 escorting CR.42s from 23^o Gruppo CT were engaged by Hurricanes of 274 Squadron five miles south-west of Gambut. During this combat Squadron Leader Patrick Dunn (P3723) reported shooting down one CR.42 and Pilot Officer Wilson (N2646) damaged another, while Flight Lieutenant Peter Wykeham-Barnes (V7558) shot down one SM.79 and damaged a second. Sottenente Sante Schiroli of the 74^a Squadriglia was shot down and killed in this combat, apparently near Bardia. Capitano Pinna claimed a Hurricane during this combat. It is not certain that Schiroli fell victim to 274 Squadron since 73 Squadron also operated in the Great Gambut area during this time and claimed victories. Sergeant Marshall (V7562/TP-A) shot down a SM.79 some 30 miles south-east of Gambut (this action was witnessed by Pilot Officer Goord). Sergeant Webster (V7551/TP-K) shot down one CR.42 in flames and damaged another ten miles to the south-east, before Pilot Officer Goord (TP-M) caught another CR.42 about 25 miles south-east of Tobruk. All these successes were achieved between 12.35 and 13.05.

At the beginning of 1942, the 23^o Gruppo joined the 18^o Gruppo to establish the 3^o Stormo again. The units reassembled at Mirafori to be re-equipped with Macchi MC.202s.

The unit returned to North Africa and took part of the Axis offensive into Egypt during the summer and fall of 1942.

On 31 August 1942 two Italian formations from 23^o Gruppo flew a fighter sweep over the front-line to protect Italian and German troops.
One eight-plane formation was led by Maggiore Luigi Filippi and the other ten-plane formation was led by Capitano Claudio Solaro.
The Italian fighters intercepted a dozen of Boston bombers escorted by two squadrons Kittyhawks. Maggiore Filippi and his formation attacked the main enemy formation while Capitano Solaro and his formation attacked a smaller group of British aircraft. The combat was fierce but lasted only a few minutes. In fact it was so short that Tenente Giorgio Solaroli who led the Italian top-cover, never got any opportunities to intervene.
During the combat Capitano Solaro, Sergente Maggiore Albani and Sergente Maggiore Celso Zemella each claimed Kittyhawks (even if Zemella claimed that his opponent had been a Spitfire). Maggiore Filippi and Capitano Pinna claimed a fourth Kittyhawk together.

On 20 October he shared in the destruction of two P-40s with Sergente Mandolesi and Capitano Giorgio Solaroli.
One of the Allied reported missing this day was Sergeant Stebbings of 260 Squadron.

At around 09:00 in the morning on 26 October seven MC.202s of the 9^o and 10^o Gruppi (Tenente Giulio Reiner (leader), Tenente Vittorio Squarcia (73^a Squadriglia), Sottotenente Giorgio Bertolaso (91^a Squadriglia), Sergente Maggiore Alessandro Bladelli, Sergente Ferruccio Terrabujo (91^a Squadriglia), Sottotenente Vittorino Daffara (97^a Squadriglia) and Sergente Maggiore Amleto Monterumici (90^a Squadriglia)) took off to intercept a reportedly eighteen Bostons, escorted by thirty P-40s and ten Spitfires, heading to bomb Fuka. A few minutes earlier, at 08:50, twelve MC.202s of the 23^o Gruppo, 3^o Stormo, (four from the 70^a Squadriglia, three of the 74^a Squadriglia and five of the 75^a Squadriglia) led by Capitano Pinna (CO of the 75^a Squadriglia) had taken off from Abu Aggag for a patrol mission (one of the aircraft was flown by Sottotenente Franco Bordoni-Bisleri of the 83^a Squadriglia, 18^o Gruppo).
Both Italian formations spotted the enemy bombers at the same time and the attack of the 4^o Stormo and the 23^o Gruppo made the bombers aiming inaccurate, so most of the bombs fell out of the target. Daffara claimed the left wingman of the head formation of Bostons, and damaged two more. Reiner strafed the bomber leader, which began to slip out of formation sideways. He then climbed and found a Spitfire in front of him, fired and hitting it. The Spitfire exploded when hitting the ground 20 kilometres south-east Fuka. Another Spitfire was claimed as a probable by Bertolaso, who also damaged two Bostons. Squarcia, after having damaged several Bostons and a P-40, pursued another Curtiss together with pilots of the 23^o Gruppo, and forced it to make a wheels-up landing south of El Daba (the pilot, Sergeant Emy Meredith, was subsequently rescued by the same Squarcia together with Maggiore Simeone Marsan in the Stormo's Fiesler Storch). Bladelli damaged four Bostons and a P-40, but was hit and had to made an emergency landing at Fuka. Another P-40, shared by many, was seen to explode when hitting the ground. Monterumici, after having fired at the bombers, was hit by three rounds from a P-40; one stopped against the head armour, one hit the armoured windshield and one destroyed the instrument panel. Monterumici recalled:

"A sharp overturn when my armoured windshield explode, whose splinters injured my face. Meanwhile, the canopy exploded too and I, while slowing down a bit to take breath, was attacked by five or six P-46 [Note: in the reports of the time, "P-46" probably meant the P-40F], that were firing at me from everywhere. Pieces of the rudder and of the right wing flew off, many bullets hit the fuselage. To escape, I decent to the ground until my propeller touched the ground. Then I shut off the engine, but the aircraft at 700 km per hour seemed to never end to skim over the desert; I'll never forget that endless run [...]"

At 06.00 on 4 November two MC.202s flown by Capitano Pinna of 74^a Squadriglia and Sergente Maggiore Francesco Cuscuna of 75^a Squadriglia were scrambled. A little later a third MC.202 took off, flown by Tenente Franco Bordoni-Bisleri of 18^o Gruppo.
They intercepted three P-40 Kittyhawks and Bordoni-Bisleri shot down one of them near their airfield at Abu Smeit. This P-40 had moments before shot down Pinna, who was forced to leave his aircraft with parachute badly wounded in his face and on his hands.
Pinna was picked up by soldiers from the Folgore Division and later collected by a Fiesler Storch. A Ca.133 Sanitario then picked him up and transported him to Marsa Matruk for treatment and recovery.
Cuscuna returned from this combat with a damaged aircraft.

During the war Pinna was awarded with two Medaglie d'argento al valore militare (Silver medals for military valour) and one Medaglia di bronzo al valore militare (Bronze medals for military valour).

Pinna ended the war with 1 biplane victory and a total of 5 destroyed.

Claims:

Kill no.	Date	Number	Type	Result	Plane type	Serial no.	Locality	Unit
	1940
	16/07/40	½	Hurricane (a)	Shared destroyed	Fiat CR.42		over Malta	70a Squadriglia
	1941
1	05/01/41	1	Hurricane (b)	Destroyed	Fiat CR.42		Gambut area	74a Squadriglia
	1942
	31/08/42	½	Kittyhawk	Shared destroyed	MC.202		North Africa	74a Squadriglia
	20/10/42	1/3	P-40	Shared destroyed	MC.202		North Africa	74a Squadriglia
	20/10/42	1/3	P-40	Shared destroyed	MC.202		North Africa	74a Squadriglia
	26/10/42	1	Boston	Probable	MC.202		Fuka area	74a Squadriglia
	26/10/42	1	Enemy fighter	Damaged	MC.202		Fuka area	74a Squadriglia

Biplane victories: 1 and 1 shared destroyed.
TOTAL: 5 and 4 shared destroyed, 1 probably destroyed, 1 damaged.
(a) Flight Lieutenant Peter Gardner Kebble of Hal Far Fighter Flight, flying in Hurricane (P2623); shot down and killed.
(b) Claimed in combat with either 274 Squadron or 73 Squadron.

Sources:
3^o Stormo, storia fotografica - Dai biplani agli aviogetti - C. Lucchini and E. Leproni, 1990 Gino Rossato Editore kindly provided by Jean Michel Cala with translations kindly provided by Birgitta Hallberg-Lombardi
Assi Italiani Della Caccia 1936-1945 - 1999 Aerofan no. 69 apr.-giu. 1999, kindly provided by Jean Michel Cala
Battle over Malta - Anthony Rogers, 2000 Sutton Publishing Limited, Gloucestershire, ISBN 0-7509-2392-X
Courage Alone - Chris Dunning, 1998 Hikoki Publications, Aldershot, ISBN 1-902109-02-3
Hurricanes over Malta - Brian Cull and Frederick Galea, 2001 Grub Street, London, ISBN 1-902304-91-8
Hurricanes over Tobruk - Brian Cull with Don Minterne, 1999 Grub Street, London, ISBN 1-902304-11-X
In cielo e in terra - Franco Pagliano, Longanesi & Co., Milano, 1969 kindly provided by Alfredo Logoluso
Italian Aces of World War 2 - Giovanni Massimello and Giorgio Apostolo, 2000 Osprey Publishing, Oxford, ISBN 1-84176-078-1
Malta: The Hurricane Years 1940-41 - Christopher Shores and Brian Cull with Nicola Malizia, 1987 Grub Street, London, ISBN 0-89747-207-1
Additional information kindly provided by Stefano Lazzaro and Ludovico Slongo.