The 71st (Forth) Heavy Anti-Aircraft Regiment, Royal Artillery was an air defence unit of Britain's Territorial Army (TA) formed in Scotland just before World War II.

The regiment was raised in the Royal Artillery (RA) 1 November 1938 as part of the expansion in Britain's anti-aircraft (AA) defences in the period of tension before World War II.

Black, and senior Major, Sir Eric Hutchison, 2nd Baronet of Hardiston, were veterans of World War I.

The Honorary Colonel was the 10th Earl of Elgin and Kincardine (who, as Major Lord Bruce, had been commander of the Highland Heavy Battery in World War I).

[10][11][12] Unlike most of Britain's defence forces, 3 AA Division was frequently in action during the so-called Phoney War that lasted from September 1939 to May 1940.

The first action occurred unexpectedly on 16 October 1939, when nine enemy aircraft suddenly appeared out of cloud and dived on warships off Rosyth Dockyard, close to the Forth Bridge.

[18][8] By October 1941, 71st HAA Rgt was part of the War Office Reserve and available for service in the field, though still in AA Command.

[15][23] The regiment was now a mobile unit under direct War Office control and was joined by its own Royal Electrical and Mechanical Engineers (REME) workshop.

[24] By November, it was fully equipped for a mobile role, with the following composition:[25] In November 1942, equipped with mobile 3-inch guns, the regiment sailed for North Africa, landing in December after Operation Torch to join 52 AA Brigade (formerly defending Edinburgh) under Allied Force Headquarters in Algeria.

When the Germans launched a counter-attack to retake Leghorn, 71 HAA responded to 104 calls for support, firing 1840 rounds.

[31] The regiment left Italy in January 1945 and returned to the UK where it rejoined Home Forces in February, preparatory to disbandment.