The Seventh Army was re-formed on 3 September 1939 as a strategic reserve force.
On 11 November, under General Henri Giraud, it became part of the 1st Army Group and was deployed to northern Belgium, under the Allied Dyle Plan.
Following the German offensives in Western Europe from 10 May 1940, the Seventh Army advanced into the Netherlands and northern Belgium under orders to join forces with Dutch troops.
After heavy fighting in Belgium and German breakthroughs further south (the Ardennes and Flanders), the general staff ordered the withdrawal of the Seventh Army headquarters (to central France).
The new Seventh Army took an active part in the Battle of France until 25 June, 1940.