'Zipper' was a British plan for the recapture of Port Swettenham and/or Port Dickson on the north-west coast of Japanese-occupied Malaya, so paving the way for an advance to the south in the direction of Singapore, which was to be taken in 'Mailfist' (spring/summer 1945).
To be co-ordinated with the 'Slippery' deception plan, the operation was devised by Admiral the Lord Louis Mountbatten’s South-East Asia Command after the receipt on 3 February 1945 of instructions to complete the liberation of Burma as rapidly as possible and then to invade Malaya with the objects of liberating that country and opening the Strait of Malacca.
The course of action likely to yield the best results appeared to be an overland advance from Burma via Tenasserim and the Kra isthmus, but it was then decided that the entire process could be speeded by the 'Roger' capture of Phuket island as a forward base and staging point, followed by the 'Zipper' capture of a lodgement in the area of Port Swettenham or Port Dickson in the north-western part of Malaya, scheduled for 9 September 1945, followed by the 'Mailfist' overland advance to the south in the direction of Singapore. A small Special Operations Executive team led by Tun Ibrahim Ismail had landed in October 1944 and managed to convince the Japanese that the landings were in fact to be made on the Kra isthmus, some 650 miles (1045 km) to the north of the area finally selected for 'Zipper'.
The opposition would have been found by Field Marshal Count Hisaichi Terauchi’s Southern Expeditionary Army Group, and more specifically by Lieutenant General Teizo Ishiguro’s 29th Army in Malaya under the command of General Seishiro Itagaki’s 7th Area Army. The 29th Army was notably small, with just two divisions and four brigades: the divisions were Lieutenant General Shichiro Kokuba’s 46th Division and Lieutenant General Yoshitsugo Inoue’s 94th Division), and the brigades Major General Yoshisuke Inoue’s 35th Independent Mixed Brigade in the Andaman islands group, Major General Toshio Itsuki’s 36th Independent Mixed Brigade in the Nicobar islands group, and the 37th Independent Mixed Brigade and 70th Independent Mixed Brigade in Malaya. The task facing the 29th Army was thus considerable, so the 7th Area Army assumed responsibility for the area between Penang and Singapore with the 46th Division, this being replaced in the 29th Army by Lieutenant General Kenryo Sato’s 37th Division from Indo-China.
'Zipper' would therefore have faced two divisions and the 70th Independent Mixed Brigade, supported by one tank battalion, in the Kra isthmus region.
The Allied landing force for 'Zipper' was fixed as Lieutenant General O. L. Roberts’s Indian XXXIV Corps comprising Major General E. C. R. Mansergh’s Indian 5th Division, Major General D. C. Hawthorn’s Indian 23rd Division, Major General G. N. Wood’s Indian 25th Division and Major General H. M. Chambers’s Indian 26th Division, Brigadier C. R. Hardy’s British 3rd Commando Brigade and one parachute brigade of Major General E. L. Bols’s British 6th Airborne Division, and though 'Zipper' itself was to use just two divisions and one brigade, the corps' additional forces were to be landed as soon as possible for 'Mailfist'.
The collapse of Japan eventually removed the urgency from 'Zipper', but the operation was undertaken in revised form advance of the original schedule as the best means of getting Allied troops back into Malaya.
'Jurist' and 'Tiderace' were therefore implemented following the surrender of Japan with the objectives of liberating Penang and Singapore respectively, followed by smaller amphibious landings on the coast of Selangor and Negeri Sembilan. Two Allied forces departed Rangoon, with the all-British Task Force 11 heading for Penang in 'Jurist', and a larger British and French force heading for Singapore in 'Tiderace'. The liberation of Penang before Singapore was not so much a reflection of the different distances to be covered but rather to test Japanese intentions as a prelude to the eventual recapture of Singapore and the rest of Malaya.
On 2 September Rear Admiral Jusaku Uozumi, the Japanese commander in north-western Malaya, signed a local surrender in Penang, a Royal Marine force taking Penang island on the following day, and on 12 September Itagaki and Vice Admiral Shigeru Fukudome, the latter commanding the 1st Southern Expeditionary Fleet respectively, represented Terauchi, who had suffered a stroke, in signing the surrender of all Japanese forces in South-East Asia.
On 9 September the Indian 25th and 23rd Divisions each landed a single brigade, one at Morib some 21 miles (34 km) to the south of Port Swettenham and the other at Sepang some 9.25 miles (15 km) to the north of Port Dickson respectively. The landings were extremely difficult as the beaches were far softer than had been expected, but the forces secured their objectives without undue difficulty as there was no opposition. The troops plus their equipment and vehicles then began to come ashore in large numbers for the reoccupation of Malaya. More than 100,000 troops were disembarked in three days from amphibious assault and other transport vessels, including the 16,738-ton British Ranchi carrying 2,968 men and supported by the 798-ton British coastal tanker Empire Tavistock, all covered by Vice Admiral H. C. T. Walker’s Force 11 (battleships Nelson and French Richelieu, light cruisers Ceylon and Nigeria, light anti-aircraft cruiser Cleopatra, 15 destroyers, and the 21st Carrier Squadron comprising the escort carriers Hunter, Stalker, Archer, Khedive, Emperor, Pursuer and, as a transport for Supermarine Spitfire fighters, Trumpeter, escorted by the light anti-aircraft cruiser Royalist.
After some delay, the British and Indian forces reached Kuala Lumpur on 12 September.