Branching out professionally, Sinnott in 1951 met with editor Stan Lee at Marvel Comics' 1950s iteration Atlas Comics, having reasoned, he recalled, "'Gee, Stan can't turn me down because he's accepting all the work we bring in'. So I went over to see Stan and he gave me a script right away..." Due to creator credits not generally being given at the time, sources differ on Sinnott's first non-Gill Atlas assignment. One standard source gives two stories published the same month: the four-page Western filler "The Man Who Wouldn't Die" in "Apache Kid" #8 (Sept. 1951), and the two-page "Under the Red Flag" in "Kent Blake of the Secret Service" #3 (Sept. 1951).