In the late 1960s, DC Comics was going through a major transition. It was trying to adapt to the major threat that it was facing from the upstart Marvel Comics, who was challenging the stronghold that DC Comics had held on the superhero comic book market since the late 1940s (in part because most companies abandoned the superhero market entirely by 1952). Carmine Infantino was named the new editorial director of the company and he set out to try to change the creative set-up at the company. Two of Infantino's biggest attempts to keep Marvel at bay was to sign away Marvel's biggest artists. The 1970 addition of Jack Kirby was the more famous move, but Infantino likely felt that he had achieved a similarly big success when he convinced Steve Ditko to join DC Comics in 1968.
Ditko was very much still a big name in comics even after leaving Marvel in 1966. He was named the top artist in the 1967 Alley Awards. So Infantino believed that it was going to be a boon for DC when Ditko joined the company in 1968. The company could not have known, however, that Ditko would be gone by the end of the year, before returning seven years later for a less celebrated return.
The story of Ditko's tenure at DC Comics is a fascinating one, as it really seems like a case of a good turn not going unpunished. With Charlton's Action Heroes line of books (based around Ditko's Captain Atom, Blue Beetle and the Question) not doing particularly well, the line closed and Charlton began to concentrate on horror and licensed comic books. Ditko was wooed to DC Comics. He initially worked for longtime DC Comics editor Murray Boltinoff. Ditko was expected to bring new characters with him and he sure did so with the introduction of the Creeper in Showcase #73 and Hawk and Dove in Showcase #75.
However, as soon as Ditko got to DC Comics, he put in a good word for his old editor at Charlton Comics, Dick Giordano, who Ditko was friends with at the time (stress "at the time") and so DC Comics hired Giordano and had him become Ditko's personal editor at DC, beginning with Showcase #75 (Giordano joined midway through the issue, so he had little impact on that specific story).
Ditko surely did not realize that getting his old friend a gig at DC Comics was going to end up negatively affecting him in the end, but that's what happened, as where Boltinoff was hand's off and allowed Ditko free rein, Giordano was anything but and that quickly led to a brief stint at DC Comics for Ditko.