The name is a sardonic reference to the "DC Explosion", a then-recent marketing campaign in which DC began publishing more monthly titles and increased the number of story pages in all of its titles, accompanied by higher cover prices. (Overall, DC premiered 57 new titles from 1975 to 1978.) Many titles which had been cancelled in the 1960s and earlier in the 1970s had been brought back as part of the "Explosion," intended to increase the company's market presence and profitability.
Since the early 1970s, DC had seen its dominance of the market overtaken by Marvel Comics, partly because Marvel had significantly increased the number of titles it published (both original material and reprint books). In large part, the DC Explosion was a plan to overtake Marvel at its own game.
DC instead experienced ongoing poor sales in winter 1977. This has been attributed in part to blizzards in 1977 and 1978, which both disrupted distribution and curtailed consumer purchases. Furthermore, the effects of ongoing economic inflation, recession, and increased paper and printing costs cut into the profitability of the entire comic book industry, coupled with steadily decreasing numbers of readers. In response, company executives ordered that titles with marginal sales and several new series still in development be cancelled. During these meetings, it was decided that DC's long-running flagship title Detective Comics was to be terminated with #480, until the decision was overturned following strenuous arguments on behalf of saving the title within the DC office, and Detective was instead merged with the better-selling Batman Family (the decision gave Detective a new lease on life and ultimately allowed the title to continue until 2011 at which point the New 52 initiative renumbered the title).
On June 22, 1978 DC Comics announced staff layoffs, and the cancellation of approximately 40% of its line.
Cancelled titles 
Twenty series were cancelled abruptly, with the following as their final issue:
- All Star Comics #74 (Sept. cover date) — #75 later published in Adventure Comics #461 and 462; the feature continued there
- Aquaman #63 (Aug./Sept.) — Aquaman story from #64 published in Adventure Comics #460
- Army at War #1 (Nov.)
- Batman Family #20 (Nov.) — merged into Detective Comics
- Battle Classics #1 (Sept.) — reprint title
- Black Lightning #11 (Sept.) — #12 later published in World's Finest Comics #260
- Claw the Unconquered #12 (Aug./Sept.)
- Doorway To Nightmare #5 (Sept.) — merged into The Unexpected
- Dynamic Classics #1 (Sept.) — reprint title
- Firestorm #5 (Oct.) — #6 reworked in The Flash #294-296. Story was published in the Firestorm: The Nuclear Man (2011) trade paperback.
- House of Secrets #154 (Oct./Nov.) — merged into The Unexpected
- Kamandi: The Last Boy on Earth #59 (Sept./Oct.) — "O.M.A.C." back-ups by Jim Starlin appeared in The Warlord #s 37-39
- Mister Miracle #25 (Sept.)
- Secret Society of Super Villains #15 (June/July) — #16 was scheduled to appear in 2007's Showcase Presents: The Secret Society of Super-Villains but said volume was indefinitely delayed. Story was reworked in Justice League of America #166-168.
- Secrets of Haunted House #14 (Oct.) — revived a year later with issue #15; the title continued until issue #46 in March 1982
- Shade, the Changing Man #8 (Aug./Sept.) — "Odd Man" story by Steve Ditko appeared in Detective Comics #487. Both the Shade and Odd Man stories were published in The Steve Ditko Omnibus Vol. 1 (2011).
- Showcase #104 (Sept.) — Deadman story for "#105" appears in Adventure Comics #464. Creeper story for #106 appears in The Creeper by Steve Ditko (2010).
- Star Hunters #7 (Oct./Nov.)
- Steel: The Indestructible Man #5 (Oct./Nov.) — #6 story reworked for All-Star Squadron #8-9
- The Witching Hour #85 (Oct.) — merged into The Unexpected
Eleven other titles were cancelled in 1978, for the most part "planned" cancellations announced in DC promos and in the final issues of the comics themselves.
- Challengers of the Unknown #87 (June/July cover date)
- DC Super Stars #18 (Jan./Feb.)
- Freedom Fighters #15 (July/Aug.) — cancelled a few months before the Implosion, to make room for other titles in the DC Explosion; storyline was to be concluded in Secret Society of Super-Villains, which itself fell victim to the Implosion
- Karate Kid #15 (July/Aug.) — cancelled a few months before the Implosion to make room for other titles in the DC Explosion; ending story published
- Metal Men #56 (February/March.) — storyline concluded with the Metal Men being recognized by UN as citizens of the world and not property.
- Our Fighting Forces #181 (Sept./Oct.)
- Return of the New Gods #19 (July/Aug.) — feature concluded in Adventure Comics #459 and 460
- Shazam! #35 (May/June) — "merged" into World's Finest Comics with #253.
- Super-Team Family #15 (Mar./Apr.) - #16 (Supergirl and Doom Patrol published in Superman Family #191-193.
- Teen Titans #53 (Feb.)
- Welcome Back, Kotter #10 (Mar./Apr.) - Final story in Limited Collectors' Edition C-57 tabloid edition.
Cancelled Comic Cavalcade 
Overall, about thirty titles were affected. Much of the unpublished work saw print in Cancelled Comic Cavalcade, a Summer 1978 two-issue ashcan "series" which "published" the work in limited quantity solely to establish the company's copyright. The title was a play on DC's 1940s series Comic Cavalcade. Some of the material already produced for the cancelled publications was later used in other series, however. The two volumes, composed of some of these stories along with earlier inventoried stories, were printed by DC staff members in black-and-white on the office photocopier. A total of 35 copies of each volume were produced, and distributed to the creators of the material, to the U.S. copyright office, and to Overstreet Comic Book Price Guide as proof of their existence. Considered a valued collectible, a set of both issues was valued as high as $3,680 in the 2011-2012 edition of the Comic Book Price Guide.
Contents ranged from completed stories to incomplete artwork. Although color covers were created, the interior pages (having been reproduced on a photocopier in the days prior to widespread use of color photocopy technology) were black and white. The first issue carried a cover price of only 10 cents, while the second carried a cover price of $1, but this was in jest, as the publication was never actually "sold".
Cancelled Comic Cavalcade contained the following material:
Issue #1 
- Black Lightning #12 (later printed in World's Finest Comics #260), cover to #13
- Claw the Unconquered #13 and #14
- The Deserter #1
- Doorway to Nightmare #6 (later printed in The Unexpected)
- Firestorm #6 (later adapted as back-up stories in The Flash)
- Green Team: Boy Millionaires #1 and #2 (to have followed a try-out in 1st Issue Special #2)
Issue #2 
- Kamandi #60 and #61 "OMAC" back-ups would also appear in Warlord #37-39 (September-November 1980)
- Prez #5
- Shade, the Changing Man #9 "The Odd Man" story would appear in Detective Comics #487 (December 1979-January 1980)
- Showcase #105 featuring Deadman, later printed slightly edited in Adventure Comics #464, #106 The Creeper
- Secret Society of Super-Villains #16, #17
- Steel #6, later reprinted with edits in All-Star Squadron #8-9 (April-May 1982)
- The Vixen #1
- covers for Army at War #2, Battle Classics #3, Demand Classics #1 and #2, Mister Miracle #26, Ragman #6, Weird Mystery Tales #25 and #26, Western Classics #1 and #2
Unpublished titles 
Among the new series planned, but never published:
- Demand Classics (reprint series) with "Flash of Two Worlds" planned for #1.
- Deserter (a Western)
- Vixen (would have been the first series starring an African-American superheroine; the character later appeared in Justice League of America). A back-up feature with Harlequin would have begun with #2.
- Western Classics (reprint series)
- Starslayer (a Mike Grell creation later published by Pacific Comics and First Comics)
Secondary features were planned, but the titles in which three were to appear were cancelled before the stories were produced; the reasons the two planned for Adventure Comics were left unreleased are unknown:
- "Manhunter from Mars" in Aquaman
- "Vigilante" in Aquaman
- "Captain Comet" in Secret Society of Super Villains
- "Metal Men" in Adventure Comics
- "The Man From Neverwhere," a creation of writer Roger McKenzie for Adventure Comics
- Adam Strange in Star Hunters. Story published in World's Finest Comics #263.
- Kahn, Jenette. "Publishorial: Onward and Upward," DC Comics cover-dated September 1978.
- Kimball, Kirk. "Secret Origins of the DC Implosion, Part One," Dial B for Blog.
- Conway, Gerry; Milgrom Al (2011). Firestorm: The Nuclear Man. DC Comics. p. 176. ISBN 1-4012-3183-7.
- Ditko, Steve (2011). The Steve Ditko Omnibus Vol. 1. DC Comics. ISBN 1-4012-3111-X.
- Ditko, Steve (2010). The Creeper by Steve Ditko. DC Comics. ISBN 1-4012-2591-8.
- "An Editorial of Sorts," Cancelled Comic Cavalcade #1 (Summer 1978): "Just to make it official -- CANCELLED COMIC CAVALCADE, Vol. 1, No. 1, Summer 1978, DC Comics, Inc.
- McAvennie, Michael; Dolan, Hannah, ed. (2010). "1970s". DC Comics Year By Year A Visual Chronicle. Dorling Kindersley. p. 179. ISBN 978-0-7566-6742-9. "With the devasting DC Implosion, a majority of the thirty-one titles terminated in 1978 were canceled in the middle of storylines. Therefore, staff members "published", in extremely limited quantities, two volumes of Cancelled Comic Cavalcade."
- Grabois, Michael. "The Deserter," Cancelled Comic Cavalcade fan page (Sept. 7, 1995). Accessed Oct. 26, 2008.
- Wells, John (October 24, 1997), "'Lost' DC: The DC Implosion", Comics Buyer's Guide (1249): 133, "The Deserter...was given his own ongoing title at the 11th hour, only to perish amidst the other cancellations. The origin of tormented Civil War deserter Aaron Hope (by Gerry Conway, Dick Ayers, and Romeo Tanghal) appeared only in Cancelled Comic Cavalcade #1."
- Wells p. 134: "After being touted in house ads during the summer, details regarding The Vixen #1 appeared in a 'Daily Planet' text page in Batman #305 and The Flash #267. Ultimately, 'Who Is The Vixen?' was printed only in Cancelled Comic Cavalcade #2."
- per Amazing Heroes #2 (July 1981) page 14: "Grell's Starslayer Debuts in July" "Starslayer, a new comic book created, written, and drawn by Mike Grell debuts in July from Pacific Comics. The series was originally offered to DC Comics but was shelved in 1978 at the time of the "DC Implosion."
See also 
- The New 52 — a 2011 promotional initiative that saw DC relaunch its entire superhero comic book line as a general "reboot" of its fictional universe and its continuity, with many comics restarting or debuting at Issue #1 and other titles being cancelled permanently or placed on hiatus.