I'm acquainted with inspector's marks,the sword has several of them along with a larger "US"-these characters are much larger,about 3/8" tall.
It was made by DJ Millard in 1862.My understanding is that is one of 10,000 made for enlisted men.Unfortunately,no scabbard.
I figure a unit marking,rack number type thing...though I've only seen a few other CW swords,none with it,I was wondering if this marking identified it as a later reissue or something.