Don't know if you're still looking, if so this may help and note that he was likely to have also been honoured by the US.
In both World Wars to today, Foreign Gallantry Awards were often bestowed by the various Allied powers to each others’ officers and men who had been involved in the same events close to or with that Country’s troops AND who had also normally been decorated by their own Country.
To wear a foreign medal in the UK, the King/Queen, and I assume the President in the USA, had to give their permission. In the UK such an award and permissions were announced in the London Gazette, I don’t know what the procedure was/is in the US.
I can’t say below is a complete list or that they are listed in the correct order but those I have seen in the London Gazette awarded to British and Colonial individuals by the French are:
The Legion d'Honneur (Legion of Honour)
5 grades but only seen these 3 awarded to British officers: Croix de Commandeur (Commander’s Cross), Croix d'0fficer (Officer’s Cross) and Croix de Chevalier (Knight’s Cross); the other 2 (highest) grades are Grand Cross, Grand Officer.
Ordre de l'Étoile Noire (Order of the Black Star)
Only seen the award at Officer grade, but there are 5:
Grand-croix (Grand cross), Commandeur avec plaque (Commander with plaque), Commandeur (Commander), Officier (Officer), and Chevalier (Knight)
Medaille d'Honneur avec Glaives (Medal of Honour with Swords)
3 classes: en argent (Silver), en bronze (bronze) or en vermeil (vermilion red).
Médaille Militaire (Military Medal)
Only issued to NCO’s and men for acts of bravery in action against an enemy force.
Croix de Guerre (War Cross)
The award represents a Mention in Dispatches and was issued with different Emblems, depending on the level of the despatch [regiment/brigade – bronze star, division – silver star], corps – silver gilt star, army – bronze palm, if 5 bronze palms awarded the palm was replaced with silver one]
If you can't establish any details for the recipient's service or US procedures for wearing foreign medals, I suggest you post on either the WW1 or WW2 Boards and I'm sure someone there will help.