Can officers in one country’s armed forces promote an enlisted person in another country’s armed forces?
Consider the following scenarios:
An American force in Afghanistan, commanded by an American officer, have a British officer (field, not staff) with them. They come under fire and the American officer is killed, as are the sergeants. The British officer takes command and needs a sergeant, so on the spot he promotes someone.
A large group of American and British POWs are in a German POW camp in WW2. There are no Allied officers, but numerous sergeants of the same rank. Can the German commandant promote one of the sergeants to Sergeant-Major?
On a related issue, in WW1 and WW2, were recommendations for medals for those in captivity passed across lines (likely via the Red Cross) and honoured and presented?