This was a British naval undertaking to run a convoy from Alexandria in northern Egypt to the besieged garrison of Tobruk farther to the west along the North African coast 12/17 October 1941).
The undertaking was created and implemented as the primary means of relieving Major General Leslie J. Morshead’s Australian 9th Division, which with Major General R. M. Scobie’s British 70th Division, General brigady Stanisław Kopański’s Free Polish Independent Carpathian Rifle Brigade and the Czechoslovak 11th Battalion – East, was holding this port behind the Axis front.
Planned as successor to 'Treacle' and 'Supercharge' (i), the operation began on 12 October as the cruiser minelayer Abdiel departed Alexandria with the destroyers Hero, Kipling and Nizam to deliver reinforcements and supplies to Tobruk. Two days later the anti-submarine whaler Soika and tug C307 departed Alexandria, the tug later returning to Mersa Matruh.
On 16 October the next phase of the operation came under attack as the convoy lost the 758-ton British tanker Pass of Balmaha and 1,208-ton Greek freighter Sámos to Korvettenkapitän Udo Heilmann’s U-97. The two vessels were to have joined the gunboat Gnat and four lighters off Mersa Matruh before proceeding to Tobruk.
The destroyers Decoy and Hasty and the escort destroyers Avon Vale and Eridge departed Alexandria, and were joined later by the destroyers Hero and Hotspur, to search for the U-boat. Hasty and Eridge were detached during the night of 17/18 October to sweep ahead of the gunboat Gnat and the four lighters, which were supported by MTB-68 and MTB-215. After an unsuccessful search, the destroyers returned to Alexandria on 18 October, and the gunboat and the lighters reached Tobruk one day later.
Meanwhile, on 17 October, the cruiser minelayer Latona, escorted by the destroyers Havock, Jackal and Nizam, had departed Alexandria with men and supplies for Tobruk, and after delivering these returned to Alexandria on 18 October, the day on which the cruiser minelayer Abdiel departed Alexandria with the destroyers Griffin, Jaguar and Kandahar to carry men and supplies to Tobruk.
On 18 October the cruiser minelayer Abdiel departed Alexandria with the destroyers Griffin, Jaguar and Kandahar with more men and supplies for Tobruk.
On the same day U-559 unsuccessfully attacked a destroyer escorting three lighters, and U-79 damaged LCT-18 while attacking Tug No. 307, LCT-13, LCT-17 and LCT-18 off Tobruk.
On 19 October the destroyers Decoy, Hasty, Havock and Hotspur departed Alexandria to shell the Axis military rest camp at Marsa Lucch during the night of 19/20 October, and later on 19 October Havock ran aground and damaged her propellers and shafts. The other destroyers escorted the damaged ship back to Alexandria and the bombardment was cancelled. The destroyers arrived back at Alexandria during the night of 20/21 October.
Also on 19 October the anti-submarine whaler Kos XIX reported a U-boat contact off Alexandria while escorting the 811-ton tanker Toneline to Tobruk. The destroyer Encounter and two anti-submarine trawlers joined the convoy to search for the U-boat, but without success, and the tanker and its escort safely reached Tobruk on 21 October.
Returning from Tobruk, the destroyer Kandahar attacked a U-boat contact off Bardia, and other movements on this day included the arrival back at Alexandria of Abdiel, Griffin, Jaguar and Kandahar.
On 20 October Latona departed Alexandria with Encounter, Kingston and Nizam, delivered their men and supplies in Tobruk, and returned to Alexandria on 21 October.
On 21 October the destroyers Jervis, Jupiter and Kandahar departed Alexandria to shell an Axis gun battery near Tobruk, a task accomplished during the night of 21/22 October. At the same time Abdiel and the destroyers Decoy, Hasty and Napier left on the sixth supply run to Tobruk, returning to Alexandria on 22 October, and the anti-submarine trawler Wolborough and steamer Gebil Kebir sailed, in company with the motor launch ML-1061, but the steamer was damaged by German bombing off Tobruk and had to be towed into harbour by the trawler. Two motor launches intended as escorts for damaged steamer were attacked by German bombers at dusk on 22 October, but sustained only light damage and both reached Tobruk.
U-79 damaged the gunboat Gnat with a torpedo some 30 miles 48 km) to the north-east of Bardia, the gunboat’s bow being blown away as far to the rear as the 6-in (152-mm) gun position. The destroyers Griffin and Jaguar from the 7th Cruiser Squadron and the destroyers Kingston and Nizam diverted from the cruiser minelayer Latona to assist Gnat. However, all the ships were ordered to turn back to the east to avoid the threat of air attack during daylight hours. Griffin and Jaguar were instructed to remain in the vicinity of Mersa Matruh, where they were joined by the escort destroyers Avon Vale and Eridge, and this destroyer group made contact with Gnat before sunset. Griffin took the damaged gunboat in tow, escorted by Jaguar and the anti-submarine whalers Southern Maid and Klo. Off Mersa Matruh the tow was turned over to the tug St Monace, and Jaguar, Avon Vale and Eridge had returned to Alexandria by 22 October.
Griffin and Jervis undertook an anti-submarine sweep ahead of the whaler Kos XIX and tanker Toneline, which had departed Tobruk at the fall of night on 22 October.
Gnat reached Alexandria on 23 October, and later an attempt was made to weld the bow of sunken gunboat Cricket to the remaining stern section of Gnat, but this was unsuccessful and the gunboat was declared a total loss.
On 22 October the cruiser minelayer Latona departed Alexandria in company with the destroyers Encounter, Hotspur and Kingston in the seventh delivery run to Tobruk. The minesweeping equipment of the minesweeping whaler Soika was cut in an air raid at Tobruk, and the cable fouled the propeller of Hotspur, which was nonetheless able to return to Alexandria at reduced speed, with no permanent damage done. The group returned to Alexandria on 23 October.
On the same day British aircraft reported a sighting of U-75, and Jupiter and Kandahar were detached to hunt for the U-boat. Another report was received some five hours later. However, Jupiter was short of fuel, and had to be sent into Alexandria, her place being taken by Decoy, which was despatched from Alexandria to join Kandahar. The sloop Flamingo, which had earlier departed Alexandria for Port Said, was also diverted to the U-boat hunt. The ships gained so success, and returned to their original tasks.
On 23 October the light cruisers Ajax, Neptune and Australian Hobart departed Alexandria with Hasty, Jupiter, Avon Vale and Eridge to bombard Axis positions at Bardia, and Hasty, Jupiter, Napier and Nizam were detached from the cruisers and undertook a separate bombardment of the Axis positions at Sollum, leaving the light cruisers to bombard Bardia escorted by Avon Vale and Eridge.
On 24 October Abdiel departed Alexandria with Griffin, Kandahar and Kingston on the ninth supply run to Tobruk, and all the ships returned to Alexandria on the following day.
On 25 October Latona departed Alexandria with Encounter, Hero and Hotspur in the tenth and final supply run of 'Cultivate'. Late in the day, Latona was dive-bombed and sunk, with the loss of 27 men, by Junkers Ju 87 dive-bombers of Hauptmann Paul-Werner Hozzel’s I/Stukageschwader 1 off Bardia, and of the escorting destroyers, Hero was damaged by a near miss, while Encounter and Hotspur escaped damage. Encounter and Hero recovered Latona's survivors for transport back to Alexandria.
On 25 October Abdiel delivered supplies and men to Tobruk, and on the same day the light cruisers Ajax, Neptune and Australian Hobart, together with the destroyers Hasty, Jaguar, Jervis, Jupiter, Kimberley, Napier and Nizam, departed Alexandria for a shore bombardment undertaking. As a result of Latona's loss, however, the undertaking was cancelled. Jaguar, Jervis, Jupiter and Kimberley were detached from the cruisers in an effort to assist Latona and then to escort Hero to Alexandria. The light cruisers bombarded Bardia, and then returned to Alexandria with Hasty, Napier and Nizam.
'Cultivate' ended on 26 October as Hero reached Alexandria for repairs, which lasted for four weeks.
As well as delivering a considerable weight of urgently needed supplies, 'Cultivate' transported 7,138 fresh troops to Tobruk, and brought back 7,234 tired troops and 727 wounded men.