During the Second World War the squadron operated as a night fighter unit, at first with the Boulton Paul Defiant and later the Bristol Beaufighter.

The squadron was formed at Pembroke, Wales, to manage a number of "Special Duties" flights that had been created for coastal operations against U-boats.

255 Squadron's first claimed strike against the enemy occurred on 14 August 1918 when Lieutenant Peebles in a DH.6 [a] attacked a submarine at periscope depth at 09:35 with a 100 lb bomb.

[8][9] The Admiralty's assessment at the time classified the result of the strike as "U-boat possibly damaged", giving the decoded position as 51°17'N, 05°04'W.

Following the final defeat of the Afrika Korps, the squadron consolidated at a single location at La Sebala II, Tunisia.

[12] Equipped with the Bolton Paul Defiant Mk.I turret fighter, the squadron used Ground-Controlled Interception (GCI) techniques to guide its aircraft toward their targets, using a procedure called "vectoring".

In effect, the GCI Station did the work of a navigator, calculating the course to steer and altitude to achieve in order to intercept the moving target.

The ground station then transmitted this information to the fighter pilot by radio; to achieve a successful interception, accurate guidance was required.

[citation needed] The night of 10/11 February 1941 saw the squadron's first combat successes, with pilots claiming two Heinkel He 111s as "probably destroyed".

[citation needed] Five Hawker Hurricane single-seat fighters were delivered to the squadron while it was at Kirton Lindsey to supplement the Defiants.

This was the most confirmed shootdowns by a British night-fighter squadron in a single night of the whole war, with congratulations received including a personal message from Sir Archibald Sinclair, the Secretary of State for Air.

Much of the Luftwaffe bomber force that had been ranged against the east coast ports of Hull and Grimsby during the squadron's time at RAF Kirton Lindsey had, in May 1941, been moved to the Russian Front ready to support Operation Barbarossa, the German invasion of Eastern Europe.

In local terms at least, the Blitz was over and apart from some token raids designed to create the pretence of ongoing strategic bombing, the night fighters guarding the ports of the Humber Estuary were left short of targets.

[citation needed] On 16 June 1941, the squadron took delivery of its first Blenheim I light bomber, for the purposes of training on twin engined aircraft prior to converting to Beaufighters.

On 14 January, a 255 Squadron crew on this rotation scored a victory over a Dornier Do.217, which was shot down off Ostend,[20][21] but overall successes remained elusive.

Once the root causes of the high accident rate amongst experienced pilots had been identified, the Air Ministry took action as soon as the aircraft supply situation permitted.

The squadron suffered 20 non-combat incidents whilst at Coltishall resulting in deaths or injury to crew members, damage to an aircraft or a forced landing away from home base.

As a security measure, the radar sets had been removed from the Beaufighters before being sent to Africa which made the squadron's attempts to defend against German night bomber attacks ineffective.

255 Squadron) was located immediately to the south-east of the town and was captured by paratroops of the British 1st Parachute Brigade on 16 November 1942.

[citation needed] Numerous skirmishes between the squadron's Beaufighters and bombers and fighter-bombers of both the Luftwaffe and the Regia Aeronautica continued throughout the month.

This marked a significant extension of the squadron's role; they were no longer just being used for defensive work, but were also carrying the fight into enemy airspace.

[citation needed] On 13 April 1943, the commanding officer received an urgent daytime request to intercept any Axis torpedo bombers that might fly west of Sardinia to try and attack a major Allied naval convoy bound for Algiers.

The primary objective of protecting the convoy was fully achieved; the remaining enemy aircraft all dropped their torpedoes, scattered and fled without ever coming within range of their target.

Over the course of the rest of the month the squadron consolidated at La Sebala II, mounting only defensive patrols against Axis bombers operating out of Sicily.

Towards the end of the month, much activity took place regarding Mk.VIII radar equipment when on 3 July two new Beaufighters arrived pre-fitted with Mk.VIII AI, beginning a complete re-equipment of the squadron.

255 Squadron received the order to move to Sicily during the evening of 9 August and on 10 July a motor convoy took 2 officers and 160 men to a staging camp.

The following day this group moved to the docks at La Goulette, then travelling to Sicily by sea in Landing Ships, Tanks (LSTs) which sailed on 14 July.

A base was set up at Bo Rizzo and the squadron reverted to a near-exclusive night air defence role for a time.

Some were in support of Yugoslav Partisans in the Balkans, some flew on into the Danube basin with the objective of destroying oil barges supplying fuel to Germany from the Romanian oil fields and some, during the autumn of 1944, headed south-east over the southern Aegean Sea with the objective of harassing the Wehrmacht's retreat from the Dodecanese Campaign.

[citation needed] The squadron operated from Foggia Main and in February 1945 it moved to Rosignamo and started to re-equip with the Mosquito XIX.