war began. In October 1939, the Commander-in-Chief, Home Forces, General Walter Kirke, was tasked with drawing up a plan, codenamed Julius Caesar, to defend the United Kingdom from a potential German invasion. As part of this plan, the division was assigned to Home Forces' reserve. It was transferred to Northern Command and moved to Charnwood Forest in Leicestershire. Here the division furthered its training, while also having to be ready to act as a counter-attack force for Julius Caesar in case of a German invasion between the Humber and The Wash. Other duties included the protection of RAF Finningley. In January 1940, the division was used to obtain drafts for formations overseas as well as volunteers to man anti-aircraft guns on small ships. In March, the division was relieved as a reserve formation. It was assigned to Eastern Command the following month, and transferred to defend the coastline of Suffolk and then Essex. These moves were part of a larger effort by Kirke to reinforce the defences in the east of England, which he believed would be the location most in danger of an invasion as a result of the German operations on mainland Europe. Other than coastal defence, the division was also responsible for guarding Ipswich Airport, constructing roadblocks inland from potential invasion beaches, and providing mobile detachments to respond to any German airborne landings. In April, following the start of the Norwegian campaign, the division organised No. 4 Independent Company, which departed for Norway on 7 May. Following the conclusion of that campaign, many of these men joined the Commandos. As a result of the German victory in France and the return of the BEF following the Dunkirk evacuation, the division was not deployed overseas per the original TA deployment timeline. The British Army began implementing lessons learnt from the campaign in France. This included a decision to base the standard division around three brigades, and the abandonment of the motor division concept. This process involved breaking up four-second-line territorial divisions to reinforce depleted formations and aid in transforming the Army's five motor divisions, each made up of two brigades, into infantry divisions made up of three brigades. As part of this process, on 23 June, the 66th Infantry Division was disbanded. This freed up the 199th Infantry Brigade and an artillery regiment to be transferred to the 55th (West Lancashire) Motor Division, which became the 55th (West