[1] Its predecessor was a horse artillery battery that was formed from Light Cavalry Squadron, HAC, in 1891.

Post-war, the battery, along with B Battery, Honourable Artillery Company, was amalgamated with the City of London Yeomanry (Rough Riders) to form the 11th (Honourable Artillery Company and City of London Yeomanry) Brigade, RHA.

[5] Each yeomanry brigade included a horse artillery battery and an ammunition column.

[3] The unit consisted of the battery and London Mounted Brigade Ammunition Column at Armoury House, Finsbury.

[7] The battery was equipped with four[5] Ehrhardt 15-pounder[8] guns and allocated as artillery support to the London Mounted Brigade.

2nd Line units performed the home defence role, although in fact most of these were also posted abroad in due course.

[9] The 1st Line battery was embodied with the London Mounted Brigade on 4 August 1914 at the outbreak of the First World War and concentrated in Berkshire.

In early April, the division starting leaving Avonmouth and the last elements landed at Alexandria before the end of the month.

By the middle of May, the horse artillery batteries were near Ismaïlia on Suez Canal Defences.

A Battery, HAC joined the division on formation and was assigned to XIX Brigade, Royal Horse Artillery (T.F.).

The battery, and its brigade, served with the Imperial Mounted Division in the Sinai and Palestine Campaign as part of the Desert Column.

With the division, it took part in the advance across the Sinai, including the First (26 – 27 March 1917) and Second Battles of Gaza (17 – 19 April 1917).

[25] The battery served with the Australian Mounted Division throughout the rest of the Sinai and Palestine Campaign.

As part of the Desert Mounted Corps, the division took part in the Third Battle of Gaza (by now re-equipped with four 13 pounders),[26] in particular the Capture of Beersheba (31 October) and the Battle of Mughar Ridge (13 and 14 November), and the defence of Jerusalem against the Turkish counter-attacks (27 November – 3 December).

The next day, a strong Turkish force attacked from the direction of Jisr ed Damiye and soon the artillery was in danger.

The brigade joined the division on East Coast Defences by June 1915 and concentrated at Aylsham with the battery at Reepham.

[33][f] 2/1st Warwickshire RHA, by now also rearmed with 18 pounders, proceeded to France on 21 June 1917 and joined the brigade there.