The 84th Searchlight Regiment (84th S/L Rgt) was an air defence unit of the British Army's Royal Artillery during World War II.

This layout was an attempt to improve the chances of picking up enemy bombers and keeping them illuminated for engagement by AA guns or night fighters.

A more serious raid on 13/14 March left many fires burning and numerous casualties, and RAF fighter and bomber stations were attacked the following night.

Fires started on 7/8 May drew enemy aircraft to the target, and many of the bombs were large Parachute mines that caused widespread damage and many casualties across the city.

[3][9] The Blitz is generally considered to have ended on 12 May,[6] but there was another significant raid on Hull on 28/29 May, mainly minelaying that caused the Humber to be closed to shipping for some time.

[3] Even after the main Blitz ended, Hull was an easy target for inexperienced Luftwaffe crews and was frequently bombed and mined.

84th took over six sites (18 S/Ls) as a temporary 'Firework' Battery (with a skeleton BHQ at 'The Elms', Ulceby, North Lincolnshire) to try to pick up German aircraft dropping mines into the Humber.

[14][15] The Luftwaffe began its so-called Baedeker Blitz in April 1942: an attack was launched against Hull on 19 May, but a fire kindled by incendiary bombs landing on an AA site outside the city distracted the bombers from their target.

[19][20][21] With the lower threat of attack by the weakened Luftwaffe, AA Command was forced to release manpower for the planned invasion of Normandy (Operation Overlord).