Central to any consideration of the introduction of African American characters into mainstream comic books of the 1960s has to be issue #6 of Sgt. Fury (March 1964), a Lee/Kirby masterpiece with inking by George Roussos. The whole series promotes a view of harmonious relations between all ethnic groups and races in America as desirable, simply by virtue of the diversity of the Howling Commandos themselves. You have a Jewish American (Izzy Cohen), Italian- (Dino Manelli), Irish- (Dum-Dum Dugan), African- (Gabriel Jones), and originally three Anglo-Americans, two from the north (Fury himself and Junior, who gets killed early in the series) and one from the South (Rebel Ralston). But issue 6 of this series is one that takes the bull of racism by the horns, brings it out in the open and slays it for all to see.
As the cover suggests, the story is "based on a little known incident of the North African campaign", so right away you know Rommell and the Afrika Korps are going to be part of the tale, and Monty's British Desert Rats are going to show up at some point. The expertise with which this story is written, though, is evident from the way the reader is led to believe that the mission to get Rommell is the main plot, and that the racist issue is a sub-plot - it's not evident at all from the cover. By the end of the book the former fizzles out and the latter provides the main punch. The story was clearly written to get a strong point across on racism.
Back to the story of issue 6. Leaving aside the details of the mission, just suffice to say it's all going on in North Africa, the Howlers are given a replacement for Junior who was lost two issues previous. Fury notices something strange about the new guy, George Stonewell. First of all Fury puts it down to their new man maybe trying to impress him with his toughness, now that he's with the Howling Commandos, but when they enter the barracks all is revealed:
Frontline Combat 15 by EC, Jan 1954) Wood used a similar scenario to undermine the stereotype of all Southerners being racists. In fact this story feels like it draws a lot of inspiration from Wood's 1954 standard setter.
Now as I'm sure anyone in the armed forces will tell you, the most important people to any soldier are the other members of his/her unit. I hasten to add that I do not speak from direct experience here, but from what I have learned from a colleague who is a veteran. Their lives are inter-dependent at a level most other people don't experience. So disharmony is, unsurprisingly, a danger to everyone concerned. A couple of times during this story the point is made that racial disharmony is a direct threat to the lives of soldiers - Stonewell, in considering himself superior to Izzy and Gabe, doesn't think them capable of handling the mission, and his clumsy attempts to take over their roles nearly gets them killed a couple of times. Here's the first incident, where mistrust of Gabriel's abilities almost ends in disaster and does reach a flashpoint between Jones and Stonewell that Fury has to break up and suppress with some serious threats:
Our Army At War 160 story "What is the Color of Your Blood?" (November 1965) featuring Jackie Johnson and the Nazi heavyweight boxer. Gabe has the same rare AB blood type as Stonewell, who won't survive without a transfusion. Sgt. Fury 6 predates OAAW 160 by 18 months, but Bob Kanigher was using the blood transfusion theme in his Sgt. Rock stories well before this issue of Sgt. Fury. Remember the story "A New Kind of War" (March 1961) featuring Sgt. Rock and the nurse in Our Army At War 104, where she offers her blood to save Rock's life? In that one I think the point was being made about the bravery of nurses in war, and their willingness to sacrifice part of what keeps them alive, or even their own life, for that of their patient. Here the blood transfusion is being used to show that there's no difference between black and white. It makes the 'one drop of blood' rule look ridiculous.