This was a British cover scheme designed to cope with any Japanese discovery of elements of Lieutenant General F. W. Messervy’s Indian IV Corps in the Myittha river valley of Burma after crossing the Irrawaddy river (December 1944/May 1945).
Related to 'Conclave', 'Pippin' and 'Stencil', the plan was designed to disguise the fact that forthcoming 'Extended Capital' offensive by Lieutenant General Sir William Slim’s 14th Army, which had crossed the Irrawaddy river to establish bridgeheads at Nyaungu and Ngazon, would be directed on a north-westerly axis toward Mandalay, and not its real south-easterly axis toward Meiktila, the strategic road and rail junction to the south of Mandalay on the route to Rangoon.
There were several deception undertakings associated with 'Extended Capital', but by far the most successful of these was 'Cloak' (ii). As such, 'Cloak' (ii) was the operational deception in support of the decisive move of the campaign, Slim’s crossing of the Irrawaddy river in February and his subsequent clearance of central Burma.
The Irrawaddy river flows to the south through Burma from the Himalayas to Rangoon. Slim’s overall plan was to cross to the eastern side of the river, defeat the Japanese forces there, and then drive down to Rangoon or Moulmein. On the eastern bank lies Mandalay, the main city of central Burma. The Japanese saw Mandalay as Slim’s initial objective, but Slim’s first target was in fact the town of Meiktila, some 70 miles (115 km) to the south of Mandalay and well back from the river, which Slim rightly saw as the key point of the Japanese supply and communications sysem in central and northern Burma.
Slim’s 14th Army comprised Messervy’s Indian IV Corps and Lieutenant General Sir Montagu Stopford’s Indian XXXIII Corps. The British general’s plan was to cross the Irrawaddy river first to the north of Mandalay with the Indian XXXIII Corps, thereby drawing Japanese attention to that direction, and then to make a surprise crossing with the IV Corps well to the south of Mandalay and drive to the south-east in the direction of Meiktila, forcing the Japanese to detach large forces to defend their communications nexus. The main drive of the 14th Army would then use the IV Corps to punch straight to the south toward Rangoon along the axis of the railway linking Mandalay and Rangoon.
On 26 February Major General T. W. Rees’s Indian 19th Division of the XXXIII Corps crossed the Irrawaddy river some 50 miles (80 km) above Mandalay and started to advance south along the eastern bank. The campaign began in earnest a little more than one week later on 8 March, when two other divisions of the Indian XXXIII Indian Corps crossed fairly close downstream of Mandalay, thus giving the impression that Slim planned a pincer movement against that city. What the Japanese thought was the IV Corps relatively close to Mandalay was in fact a bogus headquarters imitating the wireless transmissions of that formation in 'Stencil', and the strength of the corps was notionally augmented by Major General W. A. Dimoline’s 11th (East Africa) Division, a genuine formation with which the Japanese were well acquainted but which was not now at the front and was being impersonated by Brigadier T. H. S. Galletly’s 28th (East Africa) Brigade.
Meanwhile the real IV Corps made a secret wide-sweeping march under radio silence through difficult country well to the west, then swung back to the river and crossed it some 80 miles (130 km) downstream of Mandalay at Nyaungu. Its crossing was aided by 'Cloak' (ii), which was a group of deceptions designed to focus Japanese attention on the supposed IV Corps site closer to Mandalay and other crossing points, and to suggest a drive toward the oilfields farther to the south. Feints on the ground were supported by diversionary air bombardment and unconcealed photo-reconnaissance; by sonic deception including simulated noises of stores being unloaded, vehicles being concentrated, outboard engines being started, etc; by the collection of boats and the dissemination of rumours among river boatmen; and by miscellaneous timber-felling, light-flashing, dust-raising, and activity at a quickly built airstrip. There were also haversack ruses, including a map left by a party of East Africans showing the oilfield area to the south as the objective; an air drop to an imaginary agent of a radio, instructions pointing towards one of the fake crossing points, and another air drop of deceptive material seemingly from a crashed aeroplane.
On the eve of the real river crossing was a fake airborne operation using 'Paragon' dummy paratroopers with associated pyrotechnic and explosive devoices, as well as a drop of supplies to the notional air landing party.
Extensive misinformation was also fed to the Japanese by via the agency of a number of 'special means'.
Lieutenant General Shihachi Katamura’s 15th Army, within General Heitaro Kimura’s Burma Area Army, was wholly taken in by 'Cloak' (ii), and was thus persuaded that the IV Corps would attack to the north-east in the direction of Mandalay rather than to the south-east in the direction of Meiktila.
The reaction was therefore just as the 14th Army had hoped, for the Japanese prepared themselves for an offensive toward the oilfields to the south and for a pincer movement against Mandalay, believing until too late that the IV Corps' main crossing was merely an attempted feint. Soon relieved of that misconception, they fought and lost a desperate battle at Meiktila. Mandalay was in British hands by 20/21 March, and the remaining Japanese forces in central Burma were left to try to escape eastward through the Shan States (where they were threatened by 'Tarzan', 'Conclave', 'Caption' and 'Araminta') or to be shepherded to the south by Slim’s pursuit.
Slim then made his main drive toward Rangoon with the IV Corps, following the railway line to Rangoon down the Sittang river valley to the east of the mountain ridge that divides the Sittang and Irrawaddy river. The XXXIII Corps advanced to the west of this Pegu Yomas ridge along each side of the Irrawaddy river, and the object of 'Cloak' (ii) now became an attempt to persuade the Japanese to defend against this in the belief that it was Slim’s main drive. To boost its apparent strength, after the pretended 11th (East Africa) Division had been withdrawn at the end of February, the bogus Indian 18th Division was added to the XXXIII Corps' establishment.
Slim’s great 'Extended Capital' campaign culminated with the fall of Rangoon on 3 May to 'Dracula'.