Very nice button. There was a lot of history with this group. I like this part :
The regiment was originally uniformed with deep crimson facings, which in 1764 was changed to purple. The colour was often called "pompadour", from which the regiment's nickname of "The Pompadours" came. The reasons for the name of the colour are unclear; it is often said that the shade was Madame de Pompadour's favourite colour.
Some soldiers of the regiment preferred to claim that it was the colour of her underwear.