Avengers Assemble First Usage

The Internet is a repository of useless facts and trivia. One piece that's missing as far as I can tell is the first use of the Avengers catchphrase, "Avengers Assemble!"

No one's sat down to chronicle it. Having read Essential Avengers, Vol. 1, I can now fill in that gap in our knowledge. "Avengers assemble!" was first used in Avengers #10 by Thor in a battle with the Masters of Evil and Immortus.

And now, the Internet is complete...