Undistinguished Superteam Fight
After the landmark return of Captain America in issue 4 of The Avengers, the title took a slip in quality for several issues. While issues 5 through 8 still continued to introduce key characters and events that would be revisited throughout the team's history, even fans of the series generally admit this period was kind of a lull.
Issue #6 is one of these issues. It features the first time the avengers take on a supervillain group - The Masters of Evil - but neither Jack Kirby's art, nor Stan Lee's writing is particularly good. Perhaps their attentions were focused on one of the many other comics they were jointly working on at the time.
Whatever the case, completists will want to read it, but others can safely skip ahead to the next noteworthy issue, #9, which introduces the complex character Wonder Man.