'Balloon' was a British plan for the defence of Basra on the Shatt al-Arab waterway in the extreme south of Iraq during the Anglo-Iraq War (spring 1941).

Iraq lay in the area of responsibility of General Sir Archibald Wavell’s Middle East Command. Wavell despatched 'Iraq' Force under the command of Lieutenant General Sir Edward Quinan to secure Iraq, the British and Indian forces arriving by sea to seize and secure the port of Basra, which Prime Minister Winston Churchill saw as an essential supply base. 'Iraq' Force was also to reinstate a compliant Iraqi government, and to protect British interests in Iraq.

'Iraq' Force consisted of Major General W. A. K. Fraser’s Indian 10^th Division, of which only Brigadier D. Powell’s Indian 20^th Brigade was initially present after its arrival in Basra on 18/19 April. A further three ships brought in support troops on 29 April. The division’s second component, Brigadier C. J. Weld’s Indian 21^st Brigade, reached Basra early in May, and Major General W. J. Slim took command of the division in the middle of May. The division’s last component was Brigadier R. G. Mountain’s Indian 25^th Brigade, which arrived on 30 May.