On 12 June 1940, Lieutenant-General Sir Alan Brooke returned to France and next day, assumed command of all British troops still in France. He placed the British units fighting with the Tenth Army under the command of Lieutenant-General J. H. Marshall-Cornwall. This improvised formation was known as Norman Force and on 15 June comprised the 3rd Armoured Brigade of the 1st Armoured Division and the 157th (Highland Light Infantry) Brigade, 71st Field Regiment R.A. and Troop Carrying Company of the 52nd (Lowland) Infantry Division.
Next day, Brooke was able to prevent the rest of the 52nd (Lowland) Division being sent to join the 157th Infantry Brigade and during the night Brook was informed that he was no longer under French command and must prepare to withdraw the British forces from France. Marshall-Cornwall was ordered to withdraw towards Cherbourg while continuing to co-operate with the French. The rest of the 52nd (Lowland) Division was ordered back to a defence line near Cherbourg to cover the evacuation on 15 June. The AASF was also directed to send the last bomber squadrons back to Britain and use the fighter squadrons to cover the evacuations. The German advance over the Seine had paused while bridges were built but the advance began again during the day, with the 157th Infantry Brigade engaged east of Conches-en-Ouche with the Tenth Army. The army was ordered to retreat to a line from Verneuil to Argentan and the Dives river, where the British took over an 8 miles (13 km) front either side of the Mortagne-au-Perche–Verneuil-sur-Avre road. German forces followed up quickly and on 16 June, Altmayer ordered the army to retreat into the Brittany peninsula. Operation Ariel, the final Allied evacuation, had begun on 15 June.
- Alanbrooke, Field Marshal Lord (2002) . Danchev, Alex; Todman, Daniel, eds. War Diaries (Phoenix Press, London ed.). London: Weidenfeld & Nicolson. ISBN 1-84212-526-5.
- Ellis, Major L. F. (2004) [1st. pub. HMSO 1953]. Butler, J. R. M., ed. The War in France and Flanders 1939–1940. History of the Second World War United Kingdom Military Series. Naval & Military Press. ISBN 978-1-84574-056-6. Retrieved 1 September 2015.
- Supplement to The London Gazette: Operations of the British Expeditionary Force, France from 12th June, 1940 to 19th June, 1940