The first months of the Second World War were known as the Phoney War, with little significant enemy aircraft activity over Great Britain. The Battle of Dunkirk commenced at the end of May 1940, with Allied troops cut off in retreat by the German Army in north-east France, resulting in the evacuation of British troops in Operation Dynamo. During this time the RAF lost a total of 944 aircraft, with half of these being fighter aircraft. Observer Corps posts in Kent and around the Thames estuary were able to play some part in plotting aircraft while they were over south east England. This was a useful period of exposure to war-time operations for Observer Corps personnel, and one which would provide invaluable experience.