The squadron had been formed to continue the work of the development flight to use the new Leigh Light in conjunction with ASV radar on anti-submarine patrols.

The Wellington Mk XIII and later XII and XIV have been described as 'the prototype for AWACS' and 172 squadron is renowned for being the first to attack a U-boat at night using the combination of ASV and the Leigh Light.

The submarine was forced to run for safety in neutral Spain, reaching Santander by 8 June (despite two more attacks by RAF Short Sunderlands).

The first confirmed kill by 172 squadron came a month later, on 5 July, when a Wellington piloted by P/O Wiley B. Howell in 'H' for Harry, one of many Americans who had joined the RAF, sank U-502 in the Bay of Biscay.

Following the invasion of France the squadron moved to RAF Limavady in Northern Ireland to counter the U-boat threat in the North Atlantic.