102nd Heavy Anti-Aircraft Regiment, Royal Artillery, was an air defence unit of Britain's Territorial Army (TA) formed at Antrim, Northern Ireland, during the period of international tension leading up to the outbreak of World War II.

[1][2] By the time 3 AA Bde HQ returned to Belfast after the Battle of France had been lost and the BEF evacuated without its equipment, there were only seven HAA guns to defend the city.

[19] 102nd HAA Regiment had joined Middle East Forces (MEF) by late May 1943, and by early July, it had been assigned to Ninth Army in Palestine and Syria.

[20] At the end of the year, 102nd HAA Rgt was part of 1 AA Bde, which was responsible for the Levant area, including Haifa, Homs and Baalbek.

At the beginning of 1944, the Eastern Mediterranean AA Group began to be run down: the air threat had diminished and the need to provide manpower for combat tasks elsewhere had become urgent.

Surplus AA units in the region started to be disbanded;[22] 102nd HAA Rgt was placed in suspended animation on 16 January 1944 and its personnel redeployed elsewhere.

[1] When the TA was reconstituted on 1 January 1947, 102nd HAA Rgt was reformed as 502 (Ulster) (Mixed) Heavy Anti-Aircraft Regiment ('Mixed' indicating that members of the Women's Royal Army Corps were now integrated into the unit).

All the AA units in Northern Ireland were amalgamated into 245 (Ulster) Light Anti-Aircraft Regiment, to which 502 HAA Rgt contributed R Battery.