World War; and a need was seen for experimentation with and development of theories of manoeuvre and armoured warfare, as well as the creation of the short-lived Experimental Mechanized Force. The long-term impact was for the army to start to move towards mechanisation, to enhance battlefield mobility. By the 1930s, the army had established three types of divisions: the infantry division, the mobile division (later called an armoured division), and the motor division (a motorised infantry division). The primary role of the infantry division was to penetrate the enemy's defensive line, with the support of infantry tanks. Any gap created would then be exploited by mobile divisions, and the territory thus captured would be secured by the fast-moving motor divisions. These tactics would transform the attack into a break-through, while maintaining mobility. The Mobile Division was created in October 1937; it included six light tank regiments, three medium tank regiments, two motorized infantry battalions, and two artillery regiments. The light-tank units were intended for reconnaissance only. General John Burnett-Stuart, who was responsible for training the Mobile Division, stated that the infantry were not "to be put on to a position by tanks and told to hold it, and they are not meant to fight side by side with your tanks in the forefront"; the infantry's role was simply to protect the tanks when they were stationary. Burnett-Stuart's tactics did not conform with British doctrine, which promoted combined-arms co-operation to win battles, as did German armoured warfare doctrine, which held that tanks by themselves would not be a decisive weapon. However, Burnett-Stuart's thinking predominated within the British armoured forces until the doctrine was reformed in 1942. In the 1930s, tensions increased between Germany and the United Kingdom. During 1937 and 1938, German demands for the annexation of the Sudetenland in Czechoslovakia led to an international crisis. This was resolved in September 1938 by the Munich Agreement, which allowed for German annexation. Tensions did not subside, and the British government debated how best to prepare the army for war. In January 1939, the Secretary of State for War Leslie Hore-Belisha proposed splitting the Mobile Division into two smaller formations but found no support for this move. The issue was broached again a month later, and was accepted in principle by the cabinet. Shortly after, the French were informed of a preliminary timetable for the arrival of the British Expeditionary Force (BEF) in