In the late forties there was a trend at Marvel to team their superheroes with superheroines. The Human Torch was teamed with Sun Girl and the Submariner was teamed with Namora. CAPTAIN AMERICA #66 saw Captain America teamed with a new partner in place of Bucky - Golden Girl. Although she wasn't exactly new, since Golden Girl was the same girl character they'd had working with Captain America before, only in a different costumed identity.
The new team would last for several more issues, but the title was canceled in 1949, and Golden Girl was largely ignored afterwards in later revivals of the title, even though Betsy Ross was briefly brought back in the 1950's and it could be said that Sharon Carter was really Betsy Ross under a different name.
Captain America And Golden Girl: