
Avengers Assemble! Featured Cover
From David Wright:
Tales of Suspense #58 & Iron Man (Vol. 1) #228
(October 1964)
(March 1987)
Over the course of 2006, we have seen the CIVIL WAR unfold across the Marvel Universe. Standing as the leader on each side of the war is an Avenger. The large conflict of the war is personified in the conflict shown between Iron Man and Captain America. As it turns out, the idea of these two characters fighting each other has been something that's interested writers and fans for a long time. The earliest example I can find is this 1964 cover of TALES OF SUSPENSE #58, drawn by Jack Kirby. Although, be warned: You may not be able to judge the book by this cover. A certain Adaptoid told me your eyes may deceive you; you may have to read this Stan Lee tale to discover the truth.
The conflict between Cap and Shellhead was real in 1987, when Iron Man found himself in the midst of The Armor Wars, courtesy of writer David Micheline. Tony Stark's reaction to discovering many villians were using his technology led him to take actions that Steve Rogers, as The Captain, couldn't tolerate. Artist Bob Layton captures the split between these two friends in this cover of IRON MAN (Vol.1) #228,

Bonus:
...and speaking of Bob Layton, click on this thumbnail to get a good
look at his homage to the Kirby cover seen above:

Previous Featured Covers: (click on the thumbnails)