Mobilisation When war was declared on 4 August 1914, the Montgomeryshire Yeomanry mobilised at Brook Street Drill Hall with
Brevet Colonel Robert Williams-Wynn, DSO, in command. It joined the SWMB at Carmarthen and then went with it by train to
Hereford. In accordance with the
Territorial and Reserve Forces Act 1907 (
7 Edw. 7, c.9) which brought the TF into being, it 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 10 August 1914 the TF was invited to volunteer for overseas service. In the SWMB the Montgomeryshire and
Glamorgan Yeomanry signed up
en masse at Hereford, though the
Pembroke Yeomanry were less enthusiastic. On 15 August the War Office issued instructions to separate those men who had signed up for Home Service only, and form these into reserve units. On 31 August, the formation of a reserve or 2nd Line unit was authorised for each 1st Line unit where 60 per cent or more of the men had volunteered for Overseas Service. The titles of these 2nd Line units would be the same as the original, but distinguished by a '2/' prefix. In this way duplicate battalions, brigades and divisions were created, mirroring those TF formations being sent overseas. Later, the 2nd Line was prepared for overseas service and a 3rd Line was formed to act as a reserve, providing trained replacements for the 1st and 2nd Line regiments.
1/1st Montgomeryshire Yeomanry The 1/1st Montgomeryshire Yeomanry moved with the 1/1st SWMB to
East Anglia and was stationed in
Norfolk, at
Thetford by 29 August, moving to
Blickling shortly afterwards. In East Anglia the division was able to train while at the same time forming part of the defence forces for the East Coast. By September 1915 the 1/1st Montgomeryshire Yeomanry was based at
Holt. In October it moved to
Cromer. In November the 1/1st SWMB was dismounted.
Egypt and Palestine The 1/1st SWMB embarked at
Devonport on 4 March 1916 and sailed to
Egypt in company with the 1/1st
Welsh Border Mounted Brigade from 1st Mtd Division. They disembarked at
Alexandria on 14–15 March and on 20 March the two brigades were merged to form the
4th Dismounted Brigade. At first this was placed in the
Suez Canal defences under
53rd (Welsh) Division, with 1/1st Montgomeryshire Yeomanry at Beni Salama, but in April it came under the command of
Western Frontier Force. In January 1917 the dismounted yeomanry of 4th Mtd Bde were permanently re-roled as infantry. The brigade became
231st Brigade, which joined
74th (Yeomanry) Division on its formation in March 1917. On 4 March at Halmia, 1/1st Montgomeryshire Yeomanry amalgamated with
1/1st Welsh Horse Yeomanry to form
25th (Montgomery and Welsh Horse Yeomanry) Battalion, Royal Welch Fusiliers (RWF). 74th (Y) Division was in reserve for the
Second Battle of Gaza (17–19 April) and then saw action at the
Third Battle of Gaza (27 October–7 November) including the
Capture of Beersheba (31 October), where 25th RWF distinguished itself in storming the Turkish positions. It took part in the
Capture of the Sheria feature (6 November), the
Capture of Jerusalem (8–9 December) and its subsequent defence (27–30 December). Early in 1918 it fought in the
Battle of Tell 'Asur. The battalion then served though the final advance in Artois and Flanders until the
Armistice with Germany on 11 November. After the Armistice 25th RWF was reduced to
cadre in France and disbanded on 29 June 1919.
2/1st Montgomeryshire Yeomanry 2/1st Montgomeryshire Yeomanry was formed at Welshpool in September 1914 and trained with
2/1st South Wales Mounted Brigade at Carmarthen. In July 1915 2/1st SWMB moved to
Dorchester. In September 1915 it moved to
Southwold and the brigade joined 1st Mounted Division, replacing 1/1st SWMB as the latter prepared to sail to Egypt. On 4 March the regiment absorbed the
2/1st Welsh Horse Yeomanry. On 31 March 1916, the remaining mounted brigades were numbered in a single sequence and the 2/1st South Wales Mounted Brigade brigade was numbered as
4th Mounted Brigade. In April 1916, the regiment went to
Rendlesham with the brigade. In July 1916 it moved to Thornton Park near
Brentwood and joined
2nd Mounted Brigade in the new
1st Mounted Division. In October 1916 the 2/1st Montgomeryshire Yeomanry became a
cyclist unit, amalgamating with the
2/1st Denbighshire Hussars to form the
3rd (Denbigh and Montgomery) Yeomanry Cyclist Regiment in the
1st Cyclist Brigade at
Worlingham near
Beccles. In March 1917 the regiment resumed its identity as
2/1st Montgomeryshire Yeomanry, still with the 1st Cyclist Brigade, still at Worlingham. By November 1917 it was at
Gorleston where it remained until the end of the war. It was disbanded in 1919.
3/1st Montgomeryshire Yeomanry The 3rd Line regiment was formed in June 1915 at Welshpool. In July it was at
Brecon and then it was affiliated to the
6th Reserve Cavalry Regiment at
The Curragh in Ireland. By September it was at Marlborough Barracks in Dublin, later moving to Arbour Hill Barracks. It participated in the action against the
Easter Rising in Dublin in April 1916. In June 1916 the regiment was dismounted and attached to the 3rd Line Groups of the
Welsh Division at
Gobowen because its 1st Line was serving as infantry. The regiment was disbanded in January 1917 with personnel transferring to the 2/1st Montgomeryshire Yeomanry or to the
4th (Reserve) (Denbighshire) Battalion, Royal Welsh Fusiliers at
Oswestry. ==Postwar==