On the outbreak of the Second World War, the 9th Battalion was in the process of formation as a duplicate of the 8th Battalion. Based at Bulwell near Nottingham, the battalion was commanded by Claude Lancaster, MP, a former officer in the Royal Horse Guards. The battalion was assigned to the 139th Infantry Brigade, alongside the 2/5th (Derbyshire) Battalion and 2/5th Leicestershire Regiment of the 46th Infantry Division, which, like several other '2nd Line' Territorial divisions, went to join the British Expeditionary Force (BEF) in France for training and labour duties in April 1940. However, when the German Army attacked and broke through the following month, 46th Division was sent into action. On 29 May, 139 Brigade joined 'Macforce' holding the canal line near Carvin. As the 'pocket' shrank towards Dunkirk, 46th Division was ordered inside the perimeter on 27 May. On 29 May, 9th Foresters were sent to reinforce the garrison at the fortified town of Bergues, 9 km south of Dunkirk. The Germans were unable to enter Bergues until 2 June, and 9th Foresters was one of the last units to leave Dunkirk and be evacuated from France.