'Dover' was the British occupation of the Iranian port city Abadan and its oil installations within 'Countenance' (25/26 August 1941).
The campaign began on 25 August with a dawn attack by the sloop Shoreham on Abadan harbour, where the Iranian sloop Palang was quickly sunk, and remaining ships were destroyed or captured. There had been no time for the Iranians to prepare resistance.
The petroleum installations at Abadan were captured by two battalions of Brigadier R. E. Le Fleming’s Indian 24th Brigade of Major General C. O. Harvey’s Indian 8th Division, which made an amphibious crossing of the Shatt al-Arab waterway from Basra in Iraq. A small force was also landed at Bandar-e-Shahpur from the armed merchant cruiser Kanimbla to secure the port and petroleum terminal there. Aircraft of the RAF also attacked Iranian air bases and communications.