Now, the Duke was assigned to the British Military Mission to France that became the British Expeditionary Force (BEF). The BEF made up 1/10 of the allied forces aligned against the Germans. The BEF was made up of a General Headquarters, three Army Corps, and the Saar Force (troops opposite Germany's Saar Region). At the time of the German attack on 10 May 1940, BEF numbers were well above 200,000 men.
If your definition of “military command” you mean the actual leading of troops, the Duke did not lead troops in the field. However, as a Major General, he would have been at the staff officer level. Records I have do not pin down his exact job in the BEF Order of Battle, 1940. But, as a Major General in the BEF he did have a job with reporting senior officers and subordinates. Therefore, he did have a military job and was assigned to a military command.
The Duke's headquarters chateau was located north of Paris. The Germans made their major push into France (10 to 16 May 1940). On the 17th these forces began their swing to the right and drive to the coast that effectively split the allied forces in two by 21 May 1940. The Brits counterattacked at Arras but failed. The BEF commander General Gort ordered a withdrawal to the port of Dunkirk. Between 26 May and 4 June, 189,000 troops of the BEF and 140,000 French/allied troops were evacuated to England.
Although the exact date of his departure from his headquarters north of Paris is muddy, in probability it was around the 14th to 16th. Rampaging German columns would have prevented a withdrawl to the north or west, so the Duke went south and west. The entourage went first to Biarritz, then to Spain in June, and the Windsors arrived in Lisbon by July 1940.
We are done here and these proceedings are closed.
What fantasy planet are you on writing to me — or anyone — in that ludicrous pompous tone?