'Jekyll' was the British movement of the headquarters of Lieutenant General Sir Oliver Leese’s Allied Land Forces South-East Asia command from New Delhi to Barrackpore in the Bengal region of north-eastern India for better control of operations in Burma and later in Malaya (early 1945).

The 11^th Army Group was the main British command organ in the South-East Asian theatre in World War II, and although nominally a British formation, it also included large numbers of troops and formations from the British Indian Army and from British African colonies, and also Nationalist Chinese and US formations and units.

This army group had been activated in November 1943 to serve as the land forces headquarters for Admiral the Lord Louis Mountbatten’s newly created South-East Asia Command, and the army group’s commander was General Sir George Giffard, who had previously been commander-in-chief West Africa Command and commander-in-chief Eastern Army (part of GHQ India). The headquarters was initially located in New Delhi, but later moved to Kandy, Ceylon. Its responsibilities were limited to the handling of operations against Japanese forces, while GHQ India was made responsible for the rear areas and the training of the British Indian Army, although there was often overlap between the headquarters' responsibilities and (in the first year of 11^th Army Group’s existence) conflicts between their planners.

The main subordinate formations of the 11^th Army Group were the first-line 14^th Army and second-line Ceylon Army. Lieutenant General Sir Montagu Stopford’s Indian XXXIII Corps, training in southern India for amphibious operations, also came under control of the 11^th Army Group for some purposes. It would have been logical for the army group also to have had the US-led Northern Combat Area Command, under Lieutenant General Joseph W. Stilwell, under its control so that the entire Burma front would have been under a single commander.

The initial idea was that as he commanded several Chinese divisions advancing from Ledo in India to Myitkyina in Burma to cover the construction of the Ledo Road, and also had supervisory control over the large but amorphous Chinese forces attacking out of Yunnan province from the east, Stilwell was in effect an army commander. Thus, if his command came under the 11^th Army Group at the same level as the 14^th Army, the two armies' efforts could be co-ordinated at army group level.

Stilwell refused to submit 11^th Army Group control, however, for a number of reasons including the fact that he and Giffard were very different personalities and found it almost impossible to work together. Stilwell also objected to taking Giffard’s orders as he was the deputy supreme commander of SEAC and therefore in that capacity Giffard’s superior.

At a meeting to solve the resulting command problem, Stilwell, under intense pressure from Mountbatten, surprised all by saying that 'I am prepared to come under General Slim’s operational control until I get to Kamaing.' Mountbatten reluctantly agreed to this, but it was a dangerous compromise inasmuch as it created a complicated chain of command whereby Slim theoretically had to report to two different commanders in the form of Giffard for 14^th Army actions and Mountbatten for Stilwell’s formations. However, Slim was able to work with Stilwell.

Once Stilwell’s forces reached Kamaing on 20 May 1944, this arrangement ceased and Stilwell took orders only from Mountbatten, who lacked the staff (and experience) necessary to act as commander-in-chief of the Allied Land Forces.

On 12 November 1944, the 11^th Army Group was redesignated as the Allied Land Forces South-East Asia, and Leese succeeded Giffard in command.

Many of the land command problems in South-East Asia had been relieved when Stilwell was recalled to Washington on 19 October to placate Generalissimo Chiang Kai-shek, the Chinese nationalist leader who had an acrimonious relationship with Stilwell, who was also Chiang’s chief-of-staff. Stilwell’s replacement as commander of the NCAC and the administrative headquarters of the US Forces, India-Burma Theater was Lieutenant General Daniel I. Sultan. Stilwell’s replacements for his other responsibilities were Major General George C. Wedemeyer as chief-of-staff to Chiang Kai-shek and Major General Raymond A. Wheeler as Mountbatten’s deputy.

As part of the reorganisation, the NCAC was placed directly under ALFSEA, although it also received orders from Chiang. Lieutenant General Sir Philip Christison’s Indian XV Corps was removed from the 14^th Army Army and subordinated directly to ALFSEA. This corps was responsible for operations in Burma’s Arakan western coastal region, and had its own separate lines of communication and supply. Still under Slim’s command, the 14^th Army was the largest component of ALFSEA with responsibility for the 'Extended Capital' primary offensive into central Burma.

After the capture of Rangoon in May 1945, the British 12^th Army was formed in Burma under Stopford’s command, and became part of ALFSEA. The Indian XV Corps reverted to the command of the 14^th Army, which was preparing itself for the 'Zipper' amphibious operation to recover Malaya. By this time the NCAC had ceased active operations. Under acrimonious circumstances Leese was relieved and replaced as ALFSEA commander by Slim, who was succeeded at the head of the 14^th Army by Lieutenant General Sir Miles Dempsey.

After the Japanese surrender in August 1945, ALFSEA was responsible for deploying troops into Malaya, the Netherlands East Indies, Thailand and French Indo-China to disarm Japanese forces and repatriate Allied prisoners of war. The headquarters was closed later in the year.