Captain Hornby of the 4th (Royal Irish) Dragoon Guards is reputed to have been the first British soldier to kill a German soldier, using his sword, and Corporal Edward Thomas of the same regiment is reputed to have fired the first British shot shortly after 06:30 on 22 August 1914, near the Belgian village of Casteau.
Other regiments served in six brigades of the two British Indian Army cavalry divisions that were formed for service on the Western Front.
Three regiments also fought in the campaign in Mesopotamia, the only other theatre of the First World War where British cavalry served.
All but one of the thirty-two British regular army cavalry regiments fought in a recognised theatre of war, either on the Western Front or in the Mesopotamia Campaign, during which over 5,600 cavalrymen were killed, including several senior officers.
[5] Since 1880 British cavalrymen had been armed with only carbines and swords, although some carried a lance;[6] it was not until 1903 that the cavalry were issued rifles, the same ones used by the rest of the army,[7] although a version of the standard infantry rifle, the shorter-barreled LEC or "Lee-Enfield Cavalry Carbine Mark I" had been introduced in 1896.
[9] During the fighting in South Africa, it was the 7,000-strong mounted contingents, not the 5,000-strong regular cavalry, that led the way in tactical development.
[9] The regular cavalry regiments were considered so unsuitable for the current conflict that General Sir Redvers Henry Buller, commanding the advance into Northern Natal, left his six cavalry regiments behind at Ladysmith, trusting in the irregular mounted forces to carry out patrols in their stead.
[11] So effective were their tactics that they forced the British cavalry, if only for a short time, to leave their swords and lances behind and concentrate on their firepower.
On their way to relieve the siege of Kimberley, the cavalry used their horses and rifles instead of swords and lances to get behind the defending Boers.
[14] Following the Boer War there were calls for the disbandment of the cavalry by such notable persons as the Commander-in-Chief of the Forces Lord Roberts and Sir Arthur Conan Doyle.
[18] Within the year, Baden-Powell was endorsing a change in policy, recommending that instead of countering an enemy charge with a countercharge of their own, the cavalry should dismount and engage them with rifle fire.
[20] To support this change in policy, cavalrymen were now required to do two hours rifle or sword practice a day.
More than anything else, the issue of entrenching tools that were carried on the troop packhorses demonstrated how much the cavalry's doctrine had changed since the Boer Wars.
[23] In 1914, prior to the start of the First World War, there were just over 15,000 cavalrymen[23] serving in 31 British Army cavalry regiments.
[26] Several of the cavalry regiments, amounting to 6,000 men, were serving overseas in British India, South Africa, and Egypt.
[35][36] The 6th Reserve Cavalry Regiment, with 35 officers and 851 other ranks, was the largest unit then available to Dublin commander Brigadier General William Lowe of the 7th Dragoon Guards.
[47] He was replaced by William Birdwood, 12th Lancers, who had previously commanded the Australian and New Zealand Army Corps during the Gallipoli Campaign.
[52] Philip Chetwode, 19th Hussars, commanded the XX Corps in Allenby's Egyptian Expeditionary Force.
[56] Altogether during the First World War, the British cavalry provided ten corps and twenty-seven divisional commanders.
When dismounted, one man in four would be assigned to hold the horses; therefore a brigade's rifle fire was only equivalent to an infantry battalion.
[71] By now only three British cavalry regiments were not serving on the Western Front, having remained in India on internal security duties.
They did, however, see action on the North West Frontier, winning one of the eight Victoria Crosses awarded to British cavalrymen during the war.
[81] The training covered topics such as how to cross trench systems using mobile bridging equipment, tactics to employ against an entrenched enemy, blowing up and filling in trenches, and skill at arms, including machine guns and bayonet fighting.
[20] As the war progressed, the cavalrymen were issued with brodie helmets, hand grenades, trench mortars, and Hotchkiss light machine guns.
[89] The replacement of the Vickers Guns with the Hotchkiss, issued one per troop, greatly increased the firepower of the cavalry regiments.
[90] The French cuirassiers, by comparison, would not have looked out of place in the Napoleonic Wars; they still wore blue and red uniforms with breast and back metal plates and plumed brass-steel helmets.
[91] Although the trench warfare on the Western Front was dominated by the artillery and infantry, the cavalry still suffered 5,674 dead and 14,630 other casualties.
[107] In the 1920s and much of the 1930s, the General Staff tried to establish a small, mechanised, professional army; one result was the Experimental Mechanized Force.
[108] There was also a general reduction in the army, which resulted in the cavalry branch being reduced in numbers, with several famous regiments being amalgamated.