The regiment, which traces a history back to 1794, was re-formed on the creation of the Territorial Force in April 1908.
It was headquartered and had its B Squadron based at Yeomanry House, Castle Hill, Reading. A Squadron was at Windsor, C at Speenhamland (Newbury) and D at Wantage. The regiment was under command of the 2nd South Midland Mounted Brigade in the Mounted Division.
The regiment held its annual two week camp with the rest of the brigade on Salisbury Plain from 24 May 1914; the regiment was at Hamilton Camp.
1/1st Berkshire Yeomanry
5 August 1914 : began to mobilise.
September 1914 : brigade transferred to 2nd Mounted Division and moved to Churn.
8 October 1914 : regiment and rest of division were inspected by HM King George V at Churn Down.
November 1914 : moved to Fakenham in Norfolk.
9 April 1915 : embarked at Avonmouth, the brigade having been ordered to move to Egypt. Men on ship Menominee, horses and a detachment of men on Roman Prince.
20 April 1915: arrived at Alexandria and proceeded to El Zeiria. 4 May moved to Cairo and 19 July to Abbassia.
9 August 1915 : received orders to act as infantry. Reorganised with other units of the brigade into a dismounted regiment.
13 August 1915 : moved to Alexandria. Embarked onto ship Lake Michigan and sailed next day.
17 August 1915 : arrived off Mudros, trans-shipped onto ships Hythe and Sarnia and proceeded to land as Suvla Bay, Gallipoli.
21 August 1915 : regiment participated in attack across Salt Lake towards Hill 70.
1 November 1915 : evacuated from Suvla Bay and moved to Mudros.
26 November 1915 : left Mudros on ship Hannibal and landed at Alexandria 29 November, proceeding to Mena Camp.
January 1916 : brigade became an independent command and was retitled as 6th Mounted Brigade.
February 1917 : brigade transferred to Imperial Mounted Division.
June 1917 : brigade transferred to Yeomanry Mounted Division.
April 1918 : left brigade and merged with the with the Buckinghamshire Yeomanry to form C Battalion, the Machine Gun Corps.
June 1918 : moved via Italy to France.
August 1918 : renumbered 101st Battalion, the Machine Gun Corps.
Formed as a Second-Line regiment in September 1914 and remained at home throughout the war.
July 1916: converted into a Cyclist unit.
Formed as a Third-Line training unit in 1915.
Remained in United Kingdom until July 1917, when absorbed into 6th Reserve Cavalry Regiment.