'Cirrhus' was the British reoccupation of the northern part of the island of Sumatra after the surrender of the occupying Japanese forces (summer/autumn 1945).
On 4 October a convoy carrying the headquarters of Major General H. M. Chambers’s Indian 26th Division, Captain G. B. Sayer (the naval force commander), the headquarters of Brigadier H. P. L. Hutchinson’s Indian 71st Brigade, the headquarters of Brigadier T. E. D. Kelly’s Royal Artillery Indian 26th Division, 1/Lincolnshire Regiment, 6/South Wales Borderers, 1/18th Royal Garhwal Rifles and large numbers of support troops sailed from Madras for Sumatra. At sea the convoy split, the headquarters of the naval force, Indian 26th Division, Indian 71st Brigade, the Lincolns and the Garhwalis making for Padang, half-way down the south-west coast of Sumatra, while the headquarters of the Royal Artillery and the South Wales Borderers made for Medan on the north-east coast.
Each part of the convoy had five tank landing ships, some of which joined en route from Malaya, Colombo and Chittagong.
The second lift of Allied troops to Sumatra began on 29 October with the arrival at Medan from Madras of the 6/6th Rajputana Rifles (less one company already at Padang with headquarters of the Indian 26th Division) together with a company of 2nd Patiala Infantry, followed during the next few days by Brigadier J. F. R. Forman’s Indian 4th Brigade, comprising the 2/7th Rajputs, 8/8th Punjabis and 2/13th Frontier Force Rifles. The 8/8th Punjabis moved across Sumatra by road without incident to join the Indian 71st Brigade at Padang, and 6/South Wales Borderers replaced it in the Indian 4th Brigade. The forces in the area of Medan were then reorganised: the headquarters of the Royal Artillery Indian 26th Division, with the Rajputs under command, became Headquarters Medan Area responsible for the security of the town and port, while the Indian 4th Brigade was given the task of providing a striking force for operations anywhere in northern Sumatra, including keeping open the road from Medan to Fort de Kock.
During November and December the Indian 4th Brigade was reinforced by the armoured cars of A Squadron 146th Regiment Royal Armoured Corps, and the Headquarters Medan Area by the 12th Frontier Force Machine Gun Battalion, Indian 7th Field Artillery Regiment and 2nd Patiala Infantry.