An invasion scare in 1859 led to a surge of new Rifle and Artillery Volunteer corps composed of part-time soldiers eager to supplement the Regular British Army in time of need.

[3][4] The newly independent 2nd Hants had 10 batteries (termed companies from November 1891), and in 1894 these were distributed as follows:[4][7] By 1893 the War Office Mobilisation Scheme had allocated the 2nd Hampshire Artillery Volunteers to the Portsmouth fixed defences.

On 1 January 1902 the RA abandoned its divisional organisation and the unit changed its designation to 2nd Hampshire Royal Garrison Artillery (Volunteers).

[9] When the Volunteers were subsumed into the new Territorial Force (TF) under the Haldane Reforms of 1908,[10][11] Nos 1–8 companies of the 2nd Hants RGA formed 1st (Wessex) Brigade Royal Field Artillery (RFA), organised as follows:[3][7][12][13][14][15] Nos 10 and 11 Companies were separated to form the nucleus of the 2nd Wessex (Howitzer) Brigade, RFA, on the Isle of Wight.

[7][15][16][17][b] No 9 Company at Cosham also provided the nucleus of the Wessex (Hampshire) Heavy Battery, Royal Garrison Artillery.

[20][21] On mobilisation in 1914, the Territorials of the Wessex Division were sent to India to relieve British and Indian Regular troops for the Western Front.

[26][27][28][29] Initially, CCXV brigade had been equipped with obsolete 15-pounder field guns, but in July 1916 it re-equipped with 4 x 18-pounders per battery in preparation for front line duty.

[21][30] With a reformed Brigade Ammunition Column, CCXV Bde moved in October 1916 to Basra to take part in the Mesopotamian campaign, and on 8 December 1916 it joined 3rd (Lahore) Division of the Indian Army on the Tigris front.

Contact was made at Mushaid Ridge, where the force was held by heavy fire from the banks of the Euphrates Canal and from the Regulator House.

But now confusion set in: Turkish shells cut telephone wires, two forward observers were wounded, and a dust storm blew up.

[36][38] At the latter battle, CCXV and CCXXII Brigades advanced by alternate batteries over rough country under heavy enemy fire.

By now the gunners were so far forward that they were engaging at ranges of 1800–2200 yards, putting down a steady barrage on the Turkish trenches followed by 15 minutes of intense fire, described by the RA's historian, Gen Sir Martin Farndale, as 'the most accurate seen so far' on the Mesopotamian Front.

Then in July 1938 the other three batteries changed their designations, giving the brigade the following organisation on the eve of World War II:[12][7][40][13][41][42] As Britain's AA defences were expanded, on 1 April 1938 the regiment became part of the newly formed 35th Anti-Aircraft Brigade at Fareham, which soon became part of a new 5th AA Division raised in September 1938 with responsibility for the south and south-west of England.

[54][55] In October 1942, 57 (Wessex) HAA Rgt with 213, 214 and 215 Batteries was sent to North Africa to join 12 AA Bde in Eighth Army.

[50][56][57] In September 1943, 12 AA Bde including 57 HAA Rgt sailed direct from Tunisia to take part in the landings at Salerno on mainland Italy (Operation Avalanche).

When German counter-attacks threatened to break through 56th (London) Division to the beachhead on D+3, one newly arrived battery of 57 HAA Rgt was called upon to join the divisional fire-plan under control of field regiment Observation Post parties.

[58] For X Corps' crossing of the River Volturno in October, 12 AA Bde's units were deployed to protect bridges, field gun positions and landing grounds.

[59] However, the threat from the Luftwaffe declined as the campaign progressed, and the versatile 3.7-inch HAA guns began to be used in field roles as corps medium artillery.

From October to December 1943, 12 AA Bde was static, with all of its regiments and batteries engaged in corps tasks in the forward area.

[59] Once Rome was captured in June and the Germans pulled back to the Gothic Line, 12 AA Bde moved up, providing one HAA battery to each divisional artillery in X Corps, the remainder guarding airfields and river crossings in the Tiber Valley.

Unveiled in July 1994, it lists the names of six men of the battery killed during a German air raid on Portsmouth and Hayling Island on the night of 17/18 April 1941.

[69] There is also a memorial bench in Walpole Road, Gosport, dedicated to 215 Bty, 57 HAA Regiment, and the Wessex Drill Hall that stood nearby.