Experimental Mechanized Force

The Experimental Mechanized Force was a brigade-sized formation of the British Army. It was officially formed on 27 August 1927, and was intended to investigate and develop the techniques and equipment required for armoured warfare. As such it was the first armoured formation in the world. It was renamed the Experimental Armoured Force the following year. Over a period of two years, it participated in several exercises which proved the capabilities of mechanised forces against traditionally-organised and trained infantry and cavalry but also generated violent arguments within the Army. The Force was finally dispersed in February 1929. It was followed by experiments in a "Mixed Tank Brigade".

Armoured warfare theory
In the aftermath of World War I, several theorists sought ways to avoid the indecisive nature of trench warfare, with its associated heavy casualties. One weapon which had shown promise was the tank. Colonel J. F. C. Fuller, formerly the Chief of Staff of the Tank Corps, proposed an all-tank force, which would operate independently against enemy headquarters and lines of communication. More moderate theorists such as the historian and former British Army officer Basil Liddell Hart advocated mechanised forces of all arms, able to carry out operations of war other than the all-out offensive. A third influential reformer, Colonel Giffard LeQuesne Martel proposed that tanks should nevertheless be subordinated to infantry formations, while the large number of influential cavalry officers maintained that the horse still had a part to play on a modern battlefield, in spite of all evidence to the contrary on the Western Front in World War I.

Formation of the EMF
At the instigation of General George Milne, the Chief of the Imperial General Staff, the Secretary of State for War, Laming Worthington-Evans, decreed the formation of the Experimental Mechanized Force in October 1925. Milne was already inclined against the pure tank theorists, and organised the force as a balanced force of all arms, so far as resources allowed. After the units concerned had completed their training on their new equipment, the Force officially came into existence at Tidworth on Salisbury Plain in August 1927.

Colonel Fuller had originally been considered for appointment as commander of the Force but he turned it down, as it was combined with command of an infantry brigade and the administrative responsibilities connected with the garrison of Tidworth. The War Office refused to allot extra staff to assist him, and Fuller believed he would be unable to devote himself to the Force and its methods and tactics. Instead, Colonel R. J. Collins, whose professional background was light infantry and was the commander of the 7th Infantry Brigade, was appointed to command the Experimental Force.

The force was composed of:
 * Flank Reconnaissance Group; two companies of armoured cars of 3rd Battalion Royal Tank Corps (RTC)
 * Main Reconnaissance Group; 8 Carden Loyd tankettes and 8 Morris-Martel tankettes of 3rd Battalion RTC
 * Tank battalion; 5th Battalion RTC, with 48 Vickers Medium Mark I tanks
 * Mechanized Infantry Machine gun battalion; 2nd Battalion Somerset Light Infantry with Vickers machine guns carried in Crossley-Kégresse half-tracks and "6-wheel Morrises"
 * Mechanized Field Artillery Brigade (regiment); 9th Field Brigade Royal Artillery armed with QF 18 pounder field guns and QF 4.5 inch Howitzers
 * 2 batteries towed by Dragon tractors
 * 1 battery towed by Crossley-Kégresse half-tracks
 * 1 battery of self-propelled Birch Guns manned by 20 Battery, 9th Field Brigade, Royal Artillery
 * Mechanized Light Battery, Royal Artillery, equipped with 3.7 inch Mountain Howitzers portéed on Burford-Kégresse half-tracks
 * Mechanized Field Company of Royal Engineers in 6-wheel vehicles commanded by Major Martel

For a number of exercises, the 2nd Battalion Cheshire Regiment was attached to give an infantry component. When allocated, air support was provided by No. 16 (Army cooperation) Squadron, No. 3 (Fighter) Squadron and No. 11 (Bombing) Squadron of the Royal Air Force.

Exercises and results
Over the two years following its formation, the Force participated in several exercises on Salisbury Plain, the traditional training area of the British Army, which was generally open with firm going and therefore ideal for mechanised units. The Force's operations were almost invariably judged to be successful by the umpires. Its all-arms composition generally vindicated Liddell Hart's concepts, as the Force was able to undertake operations such as opposed river crossings which would have been impossible for an all-tank force. Nevertheless, Liddell Hart complained that the Force's operations were too small in scope and always served as an adjunct to larger, traditionally organised forces, rather than demonstrating that mechanised forces could operate independently and be strategically decisive.

Another shortcoming which the exercises highlighted was that the infantry's lorries could not keep up with the tanks on rough going. The solution, which would be to provide the infantry with tracked or half-tracked armoured personnel carriers, was too expensive. After the Experimental Armoured Force was disbanded, the British Army formed ad hoc armoured forces in which the Tank brigades and Motorized Infantry brigades tended to operate independently of each other, a fault repeated in the early years of World War II.