'BN' (i) was the designation of Allied convoys (together with a numerical and sometimes a literal suffix) plying the route from Bombay, India, to Aden or the Suez Canal (June 1940/April 1941).

The first of these 33 'Bombay Northward' convoys was BN.1 of 23 June/12 July 1940 with the 4,043-ton British Akbar, 3,566-ton British Alavi, 4,980-ton Norwegian Anna Odland, 7,467-ton British Beaconstreet, 7,388-ton British British Architect, 6,951-ton British British Hope, 7,616-ton Norwegian Svenor, 4,781-ton British Turbo, 6,157-ton Norwegian William Strachan and 5,916-ton British fleet auxiliary oiler Plumleaf, and escorted by the light cruisers Carlisle, Ceres and Leander, the armed merchant cruiser Cathay, the armed boarding vessel Chakdina, the destroyers Kandahar and Kingston, and the sloops Flamingo, Grimsby, Shoreham and Indian Clive and Hindustan.

The last of these convoys was BN.24 of 6/13 April 1941 with the 5,879-ton British Islami and 4,701-ton British Varsova escorted by the British light cruiser Colombo.

BN.7 was one of these convoys, and its designation is usually used for the action against a small Italian force in which it became involved on passage through the southern part of the Red Sea (20/21 October 1940).

The approaches to the Red Sea through the Gulf of Aden, the 17-mile (28-km) wide Bab el Mandeb Strait and the 1,400-mile (2255-km) passage to Suez constituted the primary British maritime route to the Middle East from East Africa, South Africa, India, the Far East and Australasia after the start of hostilities with Italy in June 1940. To the south of Suez, the British held Port Sudan about mid-way along the western coast of the Red Sea, and Aden, about 115 miles (185 km) to the east of the Bab el Mandeb Strait. About 400 miles (645 km) to the north of this strait, on the western side of the Red Sea, was the Italian naval base of Massawa in Eritrea, where Contrammiraglio Mario Bonetti commanded. This base was well sited to launch attacks on passing convoys by submarines and destroyers. The Red Sea Force, led by Rear Admiral A. J. L. Murray, based at Aden, was established in April 1940, by Vice Admiral R. Leatham, commander-in-chief of the East Indies Station.

The British closed the Red Sea to their own mercantile traffic on 24 May 1940 until convoys could be organised.

Essentially enlarged destroyers, the Italian scout cruisers Leone and Pantera possessed the unusually potent main armament of eight 4.72-in (120-mm) guns in four centreline turrets, and also carried modest anti-aircraft armament, four 21-in (533-mm) torpedo tubes and provision for 60 mines. Also based in the Red Sea, the 'Sauro' class destroyers Cesare Battisti, Daniele Manin, Francesco Nullo and Nazario Sauro each had a main armament of four 4.72-in (120-mm) guns, modest anti-aircraft armament, six 21-in (533-mm) torpedo tubes and provision for 52 mines. However, a growing list of mechanical faults, a steadily increasing shortage of fuel, and the enervating heat and humidity of the area severely degraded the capabilities of this Italian Flottiglia del Mar Rosso based at Massawa.

The BN.7 convoy heading to the north-west along the Red Sea comprised 32 British, Norwegian, French, Greek and Turkish merchant vessels escorted by the New Zealand light cruiser Leander under the command of Commander J. W. Rivett-Carnac, the British destroyer Kimberley, the British sloop Auckland, Indian sloop Indus and Australian sloop Yarra, and the British minesweepers Derby and Huntley . The convoy was nearing Perim island, which is a volcanic mass in the Bab el Mandeb Strait off the south-west coast of Yemen, during the afternoon of 19 October when an Italian aeroplane dropped four bombs which hit the water close astern of one of the merchant vessels. Leander and Auckland opened fire on the aeroplane as it headed away to the west, and shortly before the fall of night an Italian undercarriage wheel was located some 17 miles (28 km) to the south of the island. On the morning of the following day, Italian aircraft dropped four bombs, two of which fell ahead of the convoy and two bombs astern of the 17,083-ton French liner Felix Roussel, which was carrying New Zealand troops to Suez. At dusk on this same day Leander took station on the convoy’s port beam, between its charges and Massawa, and the convoy zig-zagged through the night.

The Italian flotilla departed Massawa on 20 October. The destroyers were to operate in two divisions: the slower but more heavily armed Leone and Pantera, under the commander of Capitano di Fregata Paolo Aloisi, were to divert the convoy escort, and the faster Francesco Nulla and Nazario Sauro, under the command of Capitani di Fregata Costantino Borsini and Adriano Moretti degli Adimari respectively, were to fall on the convoy in a torpedo attack. At 21.15 the two divisions divided, and at 23.21 Pantera's look-outs sighted the convoy’s smoke.

Pantera signalled Nazario Sauro and moved ahead of the convoy to effect an interception, with Leone following her. At this time the convoy was about 40 miles (65 km) to the north-north-west of Jabal al Tair island, and Leander's look-outs sighted two patches of smoke bearing north. Auckland then reported two destroyers at a range of 8,000 yards (7315 m), and Leander altered course to intercept, the captain assuming that they would turn for Massawa through the South Massawa Channel. After being challenged by Auckland, Pantera fired over Yarra at the convoy, inflicting some splinter damage to a lifeboat on one ship. Auckland opened fire and the Italian ships turned away at full speed to the west-south-west in the direction of Massawa while still firing on the convoy. The destroyers were broad on Yarra's port bow when Pantera launched two torpedoes at 23.31 and another two at 23.34. Yarra avoided these by combing their tracks. The Australian sloop’s fire-control team thought that the leading Italian destroyer was hit by the fourth or fifth salvo from the sloop’s 4-in (102-mm) guns.

Francesco Nullo and Nazario Sauro had been manoeuvring to gain a more advantageous position after receiving Pantera's sighting report, and now turned toward the convoy and sighted Leander at 01.48 on 21 October. Nazario Sauro fired a torpedo at the New Zealand cruiser, but this missed and Leander opened fire with her 6-in (152.4-mm) guns but after two minutes lost sight of Nazario Sauro, which made another torpedo attack at 02.07 and then turned toward Massawa. Francesco Nullo was not able to attack after her rudder jammed for several minutes, and lost contact with Nazario Sauro. Borsini then took his destroyer toward the cover which could be provided by the Italian batteries on Harmil island.

When the fire ceased, Leander altered course to the north-west to intercept the ships at the mouth of the South Massawa Channel (Harmil Island Passage), and at 02.45 opened fire on a ship firing red and green tracer. The range was increasing, however, and Leander lost sight of her target after the first salvoes. The cruiser altered course to the west in order to bring all her guns to bear if the ships were making for the South Massawa Channel. At 02.20 Leander illuminated Francesco Nullo with her searchlights and exchanged fire for about 10 minutes at a range of some 4,600 yards (4205 m), scoring several hits which damaged Francesco Nullo's gyrocompass and gunnery director. At 02.51 Leander lost contact in the haze and ceased fire after having fired 129 6-in (152.4-mm) rounds. Nazario Nullo headed toward Harmil island with Leander in pursuit, and at 03.00 the cruiser challenged a destroyer which, it emerged, was Kimberley, also in pursuit. After five minutes, the cruiser altered course to the east in order to rejoin the convoy as the Italian ship was drawing away at 7 kt and the convoy would be vulnerable to attack during a pursuit.

Kimberley continued at maximum speed, and at 03.50 spotted ahead of her smoke seemingly from two ships retiring at high speed. At 05.40, off Harmil island, the look-outs on Kimberely and Francesco Nullo spotted each others' ships at a range of 14,250 yards (13030 m). Borsini assumed that the ship his look-outs had seen was Nazario Sauro, but was disabused of this idea at 05.53 when Kimberley opened fire with her 4.7-in (119.4-mm) guns, taking the Italian destroyer completely by surprise. Francesco Nullo started to return fire only four minutes later. Kimberley closed the range to 5,000 yards (4570 m) and at 06.20 Francesco Nullo scraped a reef, which damaged one of her propellers, and the destroyer began to take on water. As Francesco Nullo rounded the island at about 06.25, she was hit by single shells in her forward and aft engine rooms and lost all power. Borsini ordered the ship to be abandoned, and steered toward Harmil island. The upper works were peppered by shell splinters and the crew abandoned ship as Borsini tried to run the ship aground on the island. At 06.35, Francesco Nullo was hit by the second of two torpedoes, whose detonation broke the Italian ship into two. Borsini and his first officer refused to leave the ship, and were drowned.

At 06.15 the four 4.72-in (120-mm) coast-defence guns on Harmil island had engaged Kimberley, which replied at a range of 10,000 yards (9135 m) until hit in her engine room after silencing two of the guns. Kimberley suffered three casualties.

Kimberley reported that she had been damaged and that the maximum she could make was 12 kt, and Leander left the convoy and at 06.54 increased speed to 26 kt. At 06.55 Kimberley reported that she had stopped to make repairs, that she was still under fire from the shore battery, and that the Italian had been destroyed. By 07.34, Leander was making 28.7 kt, and soon after this Kimberley signalled that she had got under way once more and was was steaming to the east at 15 kt on one engine. The shore battery’s two remaining guns maintained their fire until the range had increased to 18,590 yards (17000 m).

At 08.25 Leander was 18 miles (29 km) to the north-east of the Harmil South beacon and slowed to 10 kt. Leander now circled near Kimberley so that she had the freedom of manoeuvre should Italian bombers make an appearance. Kimberley had lost the water in her boilers and Leander despatched a boat with three shipwrights and an engine room artificer, and a wounded rating was transferred to the cruiser for medical attention. At about 10.00 Leander took Kimberley in tow.

Of Francesco Nullo's 120-man crew, the two senior officers went down with their ship, 12 men had been killed in the engagement, and 106 men were rescued by sailors of the Harmil island battery. Kimberley was out of service until 31 October, but then returned to service with a reduced maximum speed, and was fully repaired only in the spring of 1941.

In a subsequent analysis of the engagement, the British decided that they were at a disadvantage in night fighting as they were temporarily blinded by the flash of their own guns, while the Italian ships carried flashless cordite and good tracer ammunition. With the exception of Kimberley, the escorts were blamed by the headquarters at Aden for a lack of aggression, yet this ignored the risk which would have resulted from the abandonment of the convoy at night in poor visibility. So far as they were concerned, the Italians had managed to make two torpedo attacks as planned, but the division of the destroyers into two units, after previous sorties had failed to find any ships, had meant that neither had the firepower to face the British escorts.

At 10.00 on 21 October, Leander opened fire on three aircraft flying at an altitude of some 13,125 ft (4000 m), but these dropped bombs about 200 yards (185 m) ahead of the cruiser. No damage was done, and Leander and Kimberley rejoined the BN.7 convoy soon after 12.00. During the afternoon, Leander shifted the tow to Kingston, which left the convoy with Kimberley during the morning of the following day, bound for Port Sudan.

The BS.7 southbound convoy, of 20 ships, was met by the convoy escorts in the afternoon of 23 October and after an uneventful passage, dispersed to the east of Aden on 28 October. Later on 21 October, three Bristol Blenheim twin-engined light bombers of the RAF’s No. 45 Squadron located and bombed the wreck of Francesco Nullo. The Italians made another fruitless sortie on 3 December, cancelled one in January 1941 after Daniele Manin had been damaged by a bomb, and on 24 January sortied again with no result.

On the night of 2/3 February 1941, the Italian destroyers Pantera, Tigre and Nazario Sauro departed Massawa to intercept a convoy known to be in the area. This BN.14 comprised 39 merchant ships escorted by the light cruiser Caledon, destroyer Kingston and sloops Indus and Shoreham. Nazario Sauro spotted the convoy and closed to fire three torpedoes, then fired again at a ship enshrouded in smoke before turning away at high speed. The two other ships did not receive Nazario Sauro's sighting report, but 10 minutes later Pantera sighted the ships and fired torpedoes, hearing explosions and claiming probables on two merchantmen; Tigre made no contact. Close to the Massawa South Channel, Nazario Sauro encountered Kingston and, fearful of an ambush, the other Italian ships converged and called by radio for air cover at dawn before reaching port unharmed. Local Italian press reports claimed that two British ships had been hit, but this was not the case.