Use of the term, "blackguard."

[Gary]

OK, I know it was used in reference to the Royal Highlanders (42nd) in the 1700s, but what about the mid 19th Century? What does it mean? Here's the quote:

 

[roundball]

OK, I know it was used in reference to the Royal Highlanders (42nd) in the 1700s, but what about the mid 19th Century? What does it mean? Here's the quote:

 

[Gary]

Thanks Roundball! :redthumb: