In accordance with the Territorial and Reserve Forces Act 1907 which brought the Territorial Force into being, the TF was intended to be a home defence force for service during wartime and members could not be compelled to serve outside the country. However, on the outbreak of war on 4 August 1914, many members volunteered for Imperial Service. Therefore, TF units were split into 1st Line and 2nd Line units. 2nd Line units performed the home defence role, although in fact most of these were also posted abroad in due course.
1/1st Inverness-shire
The battery was embodied with the Highland Mounted Brigade on 4 August 1914 at the outbreak of the First World War. The brigade was placed under First Army of Central Force; it moved to the Huntingdon area and then to Lincolnshire in November 1914. In March 1915, the battery was attached to 2/1st South Midland Mounted Brigade in 2/2nd Mounted Division in Norfolk. The battery remained in the United Kingdom until February 1916 when it was embarked at Southampton and transported to Egypt, landing at Alexandria between 22 and 25 February 1916. ;Service with IV Brigade IV Brigade, Royal Horse Artillery was formed in April 1916 in the Egyptian Expeditionary Force with the Ayrshire and Inverness-shire Batteries, RHA. It was assigned to the ANZAC Mounted Division to provide artillery support. In practice, the batteries were permanently attached to the mounted brigades of the division and Inverness-shire RHA joined the Australian 3rd Light Horse Brigade. When the 3rd Light Horse Brigade was transferred to the Imperial Mounted Division in January 1917, it was replaced by the British 22nd Mounted Brigade. Inverness-shire RHA remained with the ANZAC Mounted Division and was attached to 22nd Mounted Brigade thereafter. The battery served with the ANZAC Mounted Division in the Sinai and Palestine Campaign throughout the rest of the war. With the division, it saw action at the Battle of Romani as part of No. 3 Section, Suez Canal Defences. This saw the repulse of the final Turkish attempt to cut the Suez Canal. The division then joined the Desert Column and with it took part in the advance across the Sinai. It fought at the Battle of Magdhaba and the Battle of Rafah. The batteries were then re-equipped with four 18 pounders each before taking part in the First and Second Battles of Gaza. ;Service with XVIII Brigade In June 1917, the Desert Column was reorganised from two mounted divisions of four brigades each to three mounted divisions of three brigades each. Consequently, the 22nd Mounted Brigade was transferred from the ANZAC to the Yeomanry Mounted Division on 6 July 1917. With a reduction to three brigades, there was a corresponding reduction in the artillery to three batteries. The Leicestershire Battery, RHA departed on 20 June to join XX Brigade, RHA in the Yeomanry Mounted Division. This led to a reorganization of ANZAC Mounted Division's artillery. A new headquarters, XVIII Brigade, Royal Horse Artillery, was formed for the division and took command of Inverness-shire and Ayrshire RHA. They were joined by Somerset RHA of III Brigade, Royal Horse Artillery. Inverness-shire RHA was now attached to the 2nd Light Horse Brigade. The batteries were still equipped with 18 pounders when the new brigade was organised but were re-equipped with 13 pounders in time for the Third Battle of Gaza at the end of October 1917. The brigade, and its batteries, remained with the ANZAC Mounted Division for 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, in particular the Capture of Beersheba and the Battle of Mughar Ridge, and the defence of Jerusalem against the Turkish counter-attacks. At the beginning of 1918, the division was attached to XX Corps and helped to capture Jericho and then formed part of Shea's Force for the First Trans-Jordan Raid. It returned to the Desert Mounted Corps for the Second Trans-Jordan Raid, the Battle of Abu Tellul and the capture of Amman. After the Armistice of Mudros, the division was withdrawn to Egypt. The Australian brigades departed for home in March and April 1919 and the New Zealanders by the end of July. The brigade was broken up some time after April 1919.
2/1st Inverness-shire
Inverness-shire RHA formed a 2nd line in 1914, initially designated as the Inverness-shire Battery RHA and later given a fractional designation as 2/1st Inverness-shire Battery, RHA. 2/1st Highland Mounted Brigade was formed in January 1915. In March 1915, the battery was attached to 2/1st South Midland Mounted Brigade in 2/2nd Mounted Division in Norfolk. It moved to Lark Hill on 18 December 1915 and spent the whole of the war in the United Kingdom.
Post war
The Inverness-shire RHA was not reconstituted until 7 February 1920 when it formed a battery in 1st Highland Brigade, Royal Field Artillery and ceased to be a Royal Horse Artillery battery. In 1939, 297 Field Battery was converted into 297 Heavy Anti-Aircraft Battery, an independent unit that later joined 101st Heavy Anti-Aircraft Regiment and fought in the defence of Scapa Flow and later in the Burma Campaign.
