In the beginning of the East African campaign of 1940-41 Maresciallo Bossi served with the 411^a Squadriglia, equipped with Fiat CR.32s.

At dawn on 19 June 1940 two Hurricanes of 1 SAAF Squadron escorted three Ju86s of 12 SAAF Squadron to attack Yavello on their first operational mission. A flight of CR.32 of the 411^a Squadriglia had recently moved to the airfield, and two of these scrambled on the approach of the South African formation. Unaware of this, the South Africans made straight for the Ca.133s of the 66^a Squadriglia, which were parked on the airfield, the Hurricanes diving down to strafe these at 09:00.
At this point the Italian fighters, flown by Tenente Aldo Meoli and Maresciallo Bossi, dived out of the sun to attack, hitting one Ju86 (they identified the bombers as Blenheims on this occasion, claiming one probably shot down) and damaged it badly, a fuel tank being holed and the gunner and observer both slightly wounded. Hurricane ‘271’ (ex. L1708) flown by Second Lieutenant Brian Llewellyn Griffiths (SAAF No. 102663) was then attacked and shot down in flames, the 23-year-old pilot from George, Cape Province, South Africa being killed. The second Hurricane, flown by Captain St. Elmo ‘Saint’ Truter (Hurricane ‘274’) became involved in a strenuous dogfight with one fighter, which Truter took to be a CR.42, and at last it reeled away, pouring smoke, landed and turned over on its back. The pilot, Tenente Meoli, was slightly wounded and the CR.32 was a complete write-off.
Throughout the combat Air Sergeant Charles Jeffries, the dorsal gunner in one of the Ju86s, had been firing at the CR.32, and he claimed that his bullets were still hitting the aircraft as it went down; his squadron subsequently maintained that he was responsible for its destruction, but the victory was credited to Truter. The two undamaged Ju86s and the remaining Hurricane returned to base, the damaged third bomber following somewhat later. Jeffries, the gunner, was later to be awarded a DFM, and was later commissioned; he would be killed in action over the Western Desert on 23 December 1941.

Bossi was later promoted to Tenente.

Tenente Bossi survived the campaign in East Africa but ended up as a PoW.

Bossi ended the war with 1 shared biplane victory.

Claims:

Kill no.	Date	Number	Type	Result	Plane type	Serial no.	Locality	Unit
	1940
	19/06/40	1/2	Ju86 (a)	Shared probable	Fiat CR.32		Yavello	411a Squadriglia
	19/06/40	1/2	Hurricane (b)	Shared destroyed	Fiat CR.32		Yavello	411a Squadriglia

Biplane victories: 1 shared destroyed, 1 shared probable.
TOTAL: 1 shared destroyed, 1 shared probable.
(a) Ju86 of 12 SAAF Squadron damaged with the gunner and observer both slightly wounded.
(b) Hurricane ‘271’ (ex. L1708) from 1 SAAF Squadron shot down. The pilot Second Lieutenant Brian Llewellyn Griffiths was killed.

Sources:
Dust Clouds in the Middle East - Christopher Shores, 1996 Grub Street, London, ISBN 1-898697-37-X
Regia Aeronautica 1935-1943 - M.Wawrzynski and Z. Lalak, 1998 kindly provided by Ondrej Repka
Springbok Fighter Victory: East Africa Volume 1 1940 – 1941 – Michael Shoeman, 2002 African Aviation Series No. 11, Freeworld Publications CC, ISBN 0-958-4388-5-4
The Commonwealth War Graves Commission
Additional information kindly provided by Massimo Indovini and Giovanni Massimello.