9th Cavalry Brigade was formed in France on 14 April 1915 with the 15th Hussars and the 19th Hussars.[2] These regular cavalry regiments had been serving on the Western Front since August 1914 as divisional cavalry squadrons assigned to infantry divisions. On the same date, 1/1st Warwickshire Battery, Royal Horse Artillery (TF) (transferred from the 2nd Cavalry Division) and a signal troop joined.
On formation, the brigade was assigned to the 1st Cavalry Division to bring it up to a three brigade standard. 1st Cavalry Division also obtained a third Cavalry Field Ambulance (9th, from England on 23 May) and a third Mobile Veterinary Section (39th, from England on 23 August).[2]
With the 1st Cavalry Division, the brigade took part in most of the major actions where cavalry could be used as a mounted mobile force.[5] At other times it formed a dismounted unit and served in the trenches (as a regiment under the command of the brigadier). Notable amongst these occasions was on 24–25 March 1918 when, in the Battle of Bapaume, the division formed a "Dismounted Division" under Brigadier-General D'Arcy Legard.[6]
By the Armistice, the division was north of Mons, about 9 miles east of Ath on the Fifth Army front. On 16 November 1918, orders were received that the 1st Cavalry Division would lead the advance of the Second Army into Germany. Moving through Namur, the division crossed the frontier on 1 December and on 7 December the brigade reached the Rhine north of Cologne. On 12 December, the brigade crossed the Rhine on the Hohenzollern Bridge and reached its position on the perimeter of the bridgehead the next day.[8]
^1/1st Bedfordshire Yeomanry left to become a cyclist unit, then to form a machine gun battalion with the 1/1st Essex Yeomanry. The German spring offensive forestalled this plan, and the regiment was remounted and returned to 1st Cavalry Division. From April 1918 it was split up with a squadron joining each regiment in 9th Cavalry Brigade (8th, 15th and 19th Hussars).[3]
^8th Hussars joined from 3rd (Ambala) Cavalry Brigade of the 5th Cavalry Division after it was broken up. On 11 March it came on the British War Establishment i.e. the 4th squadron was absorbed into the others.[2]
Becke, Major A.F. (1935). Order of Battle of Divisions Part 1. The Regular British Divisions. London: His Majesty's Stationery Office. ISBN1-871167-09-4.