A brief history
From the outbreak of the War until early 1916, six North Irish Horse Squadrons saw service beyond Irish shores.
A Squadron embarked from Dublin for Le Havre on 17 August 1914, serving as GHQ Troops until 4 January 1916, then as Divisional Cavalry to the 55th Division until 10 May 1916.
B Squadron moved from Derry to Antrim in December 1914 and in August 1915 was attached to the 59th Division in Hertfordshire. In May 1916 it was re-designated as F Squadron and apparently returned to Antrim.
C Squadron landed at Le Havre on 22 August 1914. Initially serving as Divisional Cavalry to the 5th Division, the Squadron joined A Squadron at GHQ on 12 October 1914. From 14 April 1915 to 10 May 1916 it served as Divisional Cavalry to the 3rd Division, then briefly with the 49th (West Riding) Division and 36th (Ulster) Division.
D Squadron joined the 51st (Highland) Division at Bedford before sailing for France, arriving at Le Havre on 2 May 1915. The Squadron served with the 51st Division until May 1916.
E Squadron joined the 34th Division as Divisional Cavalry in June 1915, landing at Le Havre on 12 January 1916.
F Squadron moved to Salisbury Plain in the first half of 1915 to join the 33rd Division as Divisional Cavalry. The Squadron landed at Le Havre on 17 November 1915, serving with the 33rd Division until 16 May 1916, when it joined the 49th (West Riding) Division and then the 32nd Division four days later. On 25 May 1916 it was re-designated as B Squadron.
During the first year and a half of the War, individual cavalry Squadrons had been assigned to Army Divisions. In mid-1916 this was replaced with a system of Corps Cavalry Regiments, each Regiment comprising three squadrons and a headquarters. On 10 May 1916, A, D and E Squadrons of the North Irish Horse formed the 1st Regiment North Irish Horse, which was attached to the Army's VII Corps. On 21 June 1916 the 2nd Regiment North Irish Horse was formed from C and B (formerly F) Squadrons of the North Irish Horse, and the 6th Inniskilling Dragoons (Service Squadron), and was attached to the Army's X Corps. (The Inniskilling Squadron had been formed in October 1914 from volunteers of the Inniskilling Horse of the Ulster Volunteer Force, and had arrived in France on 6 October 1915, serving as Divisional Cavalry to the 36th (Ulster) Division).
In 1917, in order to supplement depleted infantry units, it was agreed that six of the twenty cavalry regiments attached to infantry corps would be disbanded and the men trained as infantrymen. In August 1917 the 2nd Regiment North Irish Horse was dismounted, most troopers going to base for infantry training, while a party accompanied their horses to Egypt to hand over to Australian troops before returning for infantry training. In September and October the troops were absorbed into the 9th (Service) Battalion Royal Irish Fusiliers (108th Brigade, 36th (Ulster) Division), which henceforth became the 9th (North Irish Horse) Battalion Royal Irish Fusiliers. The 9th Battalion had seen much severe action since its arrival in France in late 1915, notably at the Somme in July 1916 and more recently at 3rd Ypres (Passchendaele), when on 16 August the Battalion lost 36 killed, 323 wounded, 12 cases of shell-shock, 83 missing, and 2 missing believed killed.
From February to March 1918 the V Corps Cyclist (North Irish Horse) Regiment was formed from the dismounted 1st Regiment North Irish Horse. Cyclist Regiments were some 25 per cent smaller than Cavalry Regiments, and therefore a number of officers and men were transferred to other units. At the same time, the former V Corps Cyclist Battalion was broken up, with one officer and 24 other ranks transferred-in.
Organisational timeline, 1914 to 1919
1914
19 August
A Squadron lands at Le Havre as GHQ Troops.
22 August
C Squadron lands at Le Havre as Divisional Cavalry to 5th Division.
12 October
C Squadron joins A Squadron as GHQ Troops.
1915
14 April
C Squadron transfers to 3rd Division as Divisional Cavalry.
2 May
D Squadron lands at Le Havre as Divisional Cavalry to 51st (Highland) Division.
6 October
6th Inniskilling Dragoons (Service Squadron) arrives at Le Havre as Divisional Cavalry to 36th (Ulster) Division.
17 November
F Squadron lands at Le Havre as Divisional Cavalry to 33rd Division.
1916
4 January
A Squadron transfers to 55th Division as Divisional Cavalry.
12 January
E Squadron lands at Le Havre as Divisional Cavalry to 34th Division.
12-26 April
C Squadron training with 2nd Cavalry Division.
19 April to 11 May
F Squadron training with 1st Cavalry Division.
10 May
A, D and E Squadrons form 1st Regiment, North Irish Horse, attached to VII Corps; C Squadron transfers to 49th (West Riding) Division as Divisional Cavalry.
16 May
F Squadron transfers to 49th (West Riding) Division as Divisional Cavalry.
20 May
F Squadron transfers to 32nd Division as Divisional Cavalry.
25 May
F Squadron renamed B Squadron.
1 June
C Squadron transfers to 36th (Ulster) Division as Divisional Cavalry.
21 June
B and C Squadrons and 6th Inniskilling Dragoons (Service Squadron) form 2nd Regiment, North Irish Horse, attached to X Corps.
1917
16 July
1st Regiment transfers to XIX Corps.
14 August
2nd Regiment commences dismount and transfer to infantry. 265 horses sent to Egypt via Marseilles with party under Lieutenant Leader (sailed from Marseilles on board H.T. Bohemian on 25 August).
23 August
Remainder of Regiment entrains for infantry training at 36 Infantry Base Depot, Harfleur.
5 September
67 Other Ranks supernumerary to 1st Regiment transfer to 36 Infantry Base Depot.
7 September
1st Regiment transfers to V Corps.
25 September
304 North Irish Horse Other Ranks from infantry training at Harfleur join 9th (Service) Battalion Royal Irish Fusiliers, 108th Brigade, 36th (Ulster) Division, which is renamed the 9th (North Irish Horse) Battalion Royal Irish Fusiliers.
5 October
2nd Regiment group returned from Egypt join 36 Infantry Base Depot for infantry training.
12 October
72 North Irish Horse Other Ranks join 9th (North Irish Horse) Battalion from infantry training.
1918
18-28 February
1st Regiment begins to dismount and become V Corps Cyclist Battalion (North Irish Horse).
1-13 March
1st Regiment finalises dismount. Transfers out 10 ASC drivers to A.H. Transport, 9 Officers and 63 Other Ranks to Machine Gun Base Depot, 3 Other Ranks to Cavalry Base Depot.
17 March
One Officer 24 Other Ranks transfer in from former V Corps Cyclists.
1919
9 June
Final entry in 9th Battalion RIF and V Corps Cyclist Regiment War Diaries.