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I'm kind of fascinated by the DC Implosion.
I guess it's the irony, that instead of a massive expansion, at exactly the time it was to begin, the "DC Explosion" instead went brutally the other way, with DC's parent company instead cancelling one third of the DC line.
https://en.wikipedia.org/wiki/DC_Implosion

Here's a larger version of the DC house ad I posted earlier...

[Linked Image from i.pinimg.com]



And here's another promoting the expansion of titles :

[Linked Image from 3.bp.blogspot.com]

And...

[Linked Image from ifanboy.com]

It happened in issues cover-dated Oct 1978.
And by November the explosion had imploded, with no explanation, unless you were reading the fan publications, particularly THE COMICS JOURNAL. But beyond the stuff that ran in CANCELLED COMIC CAVALCADE, there was still a year's worth of inventory material to burn up in the now thinned down DC titles, so freelancers were forced to migrate over to Marvel for work. Guys like Michael Golden, Bob Wiacek, Al Milgrom, Bob McLeod, Jerry Bingham, Dave Michelinie, Bob Layton and many others. Which was really good fortune for Marvel, because these talents began a renaissance on the tiltes they took over at Marvel, particularly CAPTAIN MARVEL, SPECTACULAR SPIDER-MAN, IRON MAN, and MICRONAUTS.

At DC, there were a few issues where the Implosion hit so fast, that they ran house ads for titles that were never actually published.
One in JLA issue 159, Oct 1978, where a full page ad appears with covers shown for SHOWCASE 105 (DEADMAN), DEMAND CLASSICS (a planned reprint title), WESTERN CLASSICS (another planned reprint title), and VIXEN issue 1. None of which were actually published, but later collected in xerox form in CANCELLED COMIC CAVALCADE vol. 2.

Then in JLA 160 (Nov 1978), no mention whatsoever of the "DC Explosion' or its unforseen implosion.
With BATMAN FAMILY cancelled afer issue 20, the inventory material instead appeared in DETECTIVE COMICS 481 and 482, with some really nice material by O'Neil, Rogers, Golden, Giordano, Starlin and Russell. Subsequent DETECTIVE issues with inventory material were far less impressive.

The last RETURN OF THE NEW GODS unpublished issue by Conway and Newton was split in 2 parts, and ran in ADVENTURE COMICS 459 and 460, with truly awful inking.

"Black Lightning" by Mike Nasser appeared in CANCELLED COMIC CAVALCADE in xerox form, and then about a year later appeared in color as a backup in WORLD'S FINEST.

An OMAC backup began in KAMANDI 59 in Oct 1978, but the series was cancelled in the Implosion. CANCELLED COMIC CAVALCADE ran KAMANDI 60 and 61 story in xerox form, that also included an unpublished Kirby story that would in 1976 have been SANDMAN 7 ("The Seal Men's War on Santa Claus") , but with the 1978 Implosion was again prevented from being published as a color comic issue.
It appeared in CCC in xerox form in 1978, and then finally in color in BEST OF DC digest 22, in 1982.

The three-part Starlin OMAC backup finally fully ran in WARLORD 37-39 in late 1980 (WARLORD 37 repeats the 8-page OMAC backup story published in KAMANDI 59, inked by Joe Rubinstein. WARLORD 38 and 39 present the other 2 chapters by Starlin, but very disappointingly inked by Romeo Tanghal. )

Beyond that, not much impressed me in this mass of cancelled material. It's still interesting to see, but there wasn't much that really stood out.

Post-implosion, I liked the new title TIME WARP 1-5 (a thick dollar comic of SF anthology stories, all 5 with dynamite pulp-ish Kaluta covers).
And then when that was cancelled, it was replaced by a thinned-down regular 36-page formatted MYSTERY IN SPACE anthology, that ran from 111-117, that despite some nice art and interesting stories, didn't survive in a standard comic size format either.

It was only in 1980-1982, witth Starlin in DC COMICS PRESENTS 26-29 and 36-37, Wolfman and Perez on NEW TEEN TITANS, Conway and Perez on JLA, Levitz and Giffen on LEGION OF SUPERHEROES, Pasko and Giffen "Dr Fate" backups in FLASH 306-313, Thomas/Colon/Dezuniga on ARAK, plus ARION by Duursema, and other new material at that time, that DC really fully recovered from the Implosion.