Osvaldo Bertolaccini was born on 27 February 1941 in Pietrasanta.

In January 1941, Bertolaccini served in 364^a Squadriglia, 150^o Gruppo Autonomo C.T. in the Greek campaign. This unit was at the time equipped with Fiat CR.42 and operated from Valona, Albania.

At 09:40 on 6 January 1941 nine Blenheims from 211 Squadron appeared over Valona, bombing the foreshore from 4000 feet. CR.42s of 150^o Gruppo and G.50bis from 154^o Gruppo were scrambled, intercepting as the bombers left the target.
154^o Gruppo claimed two of the Blenheims shot down, one of them apparently being Flying Officer R. D. Cambell’s L1487. All three of the Blenheim crew were captured.
Meanwhile the CR.42 pilots had kept up the pursuit, returning to claim four more Blenheims shot down, three of them by Sergente Bertolaccini and one by Sottotenente Pasquale Faltoni.
Sergeant J. R. Marshall's L1542 had been slightly damaged in the tail by AA when a CR.42 attacked, but the gunner, Sergeant Bill Baird, drove this off, reporting that smoke poured from its engine as it broke away. L8536, flown by Flying Officer L. S. Delaney, was badly hit, although Sergeant T. A. McCord in the turret claimed that he believed he had shot down a 'Macchi' in flames. As the bomber headed away, the port engine stopped, but it headed on, accompanied by the formation leader, Flight Lieutenant Doudney, whose Blenheim had also been heavily damaged. Near the frontier Delaney indicated that he was going down to land. As he attempted to bring the aircraft down on its belly, it struck some boulders and cartwheeled. The crew were killed outright. Doudney almost reached Menidi, but he too was obliged to crash-land short of this base. Two more Blenheims also received damage, Flying Officer L. B. Buchanan reaching Menidi, while Pilot Officer J. C. Cox put down at Eleusis for temporary repairs.
Losses were thus one Blenheim over the target and two crash-landed, one of them totally destroyed as a result, plus two more damaged against Italian claims for six destroyed and one damaged.

At 15:00 on 27 February, nine Blenheims, six from 211 Squadron and three from 11 Squadron, set off to bomb Valona, escorted by five 80 Squadron Hurricanes and four more from 33 Squadron. An hour later, as the formation arrived over Valona, 13 CR.42s of the 150^o Gruppo attacked as the Blenheims were bombing. Although the Hurricane escort engaged them at once, some got through to the bombers and damaged five of them, including all three of the 11 Squadron machines. Two of these (N5379 and T2399) would crash-land on return to Paramythia, both having suffered heavy damage to their hydraulic systems and both were written off. The Hurricanes meanwhile had become involved in a heavy battle with the Fiats during which seven of the Italian fighters were claimed shot down, and two more were reported to have collided with each other after being attacked by Sergeant Edward Hewett and crashed. Claims were made by Flight Lieutenant 'Pat' Pattle, Flying Officer Nigel Cullen, Sergeant Hewett (two), Flying Officer Richard Acworth, and Flying Officer Wanklyn Flower, who shared one with a 33 Squadron pilot, believed to have been Flying Officer H. J. Starrett. The seventh claim was believed to have been made by 33's Flight Sergeant Leonard Cottingham.
In the event it seems that only two CR.42s were lost but it hit the 364^a Squadriglia, which had scrambled three fighters since both of them were from the unit. Sottotenente Pasquale Faltoni, the formation leader, baling out after suffering wounds, as did Sergente Bertolaccini, who was almost dead when he hit the ground. Sergente Bertolaccini later succumbed to his wounds. The Italians made no claims and believed that their attackers had been Spitfires (this indicates that Bertolaccini actually shot down two Blenheims and thus made an ace before dying). Pattle’s Hurricane suffered a single bullet through the petrol tank - the only damage recorded to the British fighters. A further CR.42 of the Gruppo's 364^a Squadriglia was destroyed on the ground by the Blenheims’ bombs, and several others were damaged. A dozen drums of fuel went up in flames, and two airmen were wounded.
Pilot Officer Geary, gunner in Blenheim L1481 of the 211 Squadron, recorded his impressions of the raid:

“I had a grandstand view of the whole affair. It was lovely bombing - direct hits all over the aerodrome and on buildings. A large formation of CR42s took of to intercept us. One got on my tail, so I put a burst into him, and he fell away. Then two Hurricanes appeared in a flash, and well, he just fell to pieces. The Hurricanes wheeled and proceeded to deal with the others. The sky was full of crashing aircraft - and they were all enemy. We had a most pleasant tour home, and the scenery looked more lovely than ever.”

At the time of his death, Bertolaccini was credited with 5 biplane victories.

Claims:

Kill no.	Date	Time	Number	Type	Result	Plane type	Serial no.	Locality	Unit
	1941
1	06/01/41		1	Blenheim (a)	Destroyed	Fiat CR.42		Valona	364a Squadriglia
2	06/01/41		1	Blenheim (a)	Destroyed	Fiat CR.42		Valona	364a Squadriglia
3	06/01/41		1	Blenheim (a)	Destroyed	Fiat CR.42		Valona	364a Squadriglia
4	27/02/41	16:00	1	Blenheim (b)	Destroyed	Fiat CR.42		Valona	364a Squadriglia
5	27/02/41	16:00	1	Blenheim (b)	Destroyed	Fiat CR.42		Valona	364a Squadriglia

Biplane victories: 5 destroyed.
TOTAL: 5 destroyed.
(a) Claimed in combat with Blenheims from 211 Squadron, which lost one Blenheim over the target and two crash-landed, one of them totally destroyed as a result, plus two more damaged against Italian claims for six destroyed and one damaged.
(b) Claimed in combat with Blenheims from 11 Squadron, which lost N5379 and T2399 that were both lost after wheels-up landing back at base.

Sources:
53^o Stormo - Marco Mattioli, 2010 Osprey Publishing, Oxford, ISBN 978-1-84603-977-5
Air war for Yugoslavia, Greece and Crete - Christopher Shores, Brian Cull and Nicola Malizia, 1987 Grub Street, London, ISBN 0-948817-07-0
Fiat CR.42 Aces of World War 2 - Håkan Gustavsson and Ludovico Slongo, 2009 Osprey Publishing, Oxford, ISBN 978-1-84603-427-5
Ministero della Difesa
Additional information kindly provided by Giovanni Massimello.