African settings was culturally outdated to the point of being incongruous. Marvel responded by assigning McGregor to write original material for Jungle Action, with the only creative restriction being that the stories must be set in Africa. Thus an actual African protagonist, the superhero the Black Panther, took over the starring feature with issue #5, a reprint of the Panther-centric story in the superhero-team comic The Avengers #62 (March 1969). A new series began running the following issue, written by McGregor, with art by pencilers Rich Buckler, Gil Kane, and Billy Graham, and which gave inkers Klaus Janson and Bob McLeod some of their first professional exposure. Comics historian Les Daniels observed that "the scripts by Don McGregor emphasized the character's innate dignity". The critically well-received series ran in Jungle Action #6–24 (Sept. 1973– Nov. 1976). One now-common innovation McGregor pioneered was that of the self-contained, multi-issue story arc. The first, "Panther's Rage", ran through the first 13 issues, initially as 13- to 15-page stories. Starting with Jungle Action #14, they were expanded to 18- to 19-page stories; there was additionally a 17-page epilogue. The length of the story arc coupled with the series' bimonthly schedule made it difficult for readers to keep characters and subplots fresh in their memories, but Jungle Action nonetheless maintained passable if modest sales and was popular with the desirable college-student demographic. Two decades later, writer Christopher Priest's 1998 series The Black Panther utilized Erik Killmonger, Venomm, and other characters introduced in this arc. Critic Jason Sacks has called the arc "Marvel's first graphic novel", saying: The second and final arc, "Panther vs. the Klan", ran as mostly 17-page stories in Jungle Action #19–24 (Jan.–Nov. 1976), except for issue #23, a reprint of Daredevil #69 (Oct. 1970), in which the Black Panther guest-starred. The subject matter of the Ku Klux Klan was considered controversial in the Marvel offices at the time, creating difficulties for the creative team. Writer Dwayne McDuffie said of the Jungle Action "Black Panther" series: Due to low sales and deadline problems, Jungle Action was cancelled with issue #24. "Panther vs. the Klan" was abandoned mid-story and Marvel relaunched the Black Panther in a self-titled series, with Jack Kirby – newly returned to Marvel after having decamped to rival DC Comics for a time – as writer, artist, and editor starting with cover-date January 1977. Marvel reasoned that though Jungle Action was