The text accompanying Plates 449 and 450 doesnot give any significance to the crescent. They do say that the officers of the 1st SC had crossed scimitars within the "horns" of the crescent. There are plenty of references provided and the answer on the significance of the crescent may lie therein.
The notes do specify that all officers were to provide themselves with a gorget, which was the symbol of being an officer in both the American and British army for this time period. There is a footnote, #11, to the source, but the footnotes stop at 7. I know they are eventually published. Since I am working through the issues systematiclly, when I find footnote #11, I will post it for you. In case you have access, the volume & issue number in which this all appears is Vol. 29, No. 2, p. 70.
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