While the JLA and JSA team ups usually got more attention, that tradition began with the Flashes of two worlds, Jay Garrick and Barry Allen, teaming up for a few times.
Then, they got comfortable, and brought in their friends, and those friends, like the Green Lanterns of two Earths, as well as JSAers Dr. Fate and Hourman as well as Starman and Black Canary, had team ups of their own....
Flash Of Two Worlds
This was the big one. The first time Barry met Jay, in
Flash #123 (September, 1961) by
Gardner Fox,
Carmine Infantino and
Joe Giella (with
Infantino and
Murphy Anderson supplying the cover).
While helping Iris by putting on a show as the Flash at the Central City Community Center, Barry ends up on another Earth, that had subtle differences. The big difference between Earths was that Jay Garrick had been the Flash in Keystone City, and had retired for a time. But, with his old foes on the loose (Thinker, Fiddler and the Shade), Jay was coaxed back into action by Barry, and the two Flashes defeated the three villains, with Barry vibrating home at the end (and Jay watching, so he'd know how to do that trick.
This was the first appearance of the
Flash (Jay Garrick), his wife (Joan Garrick) and the
Fiddler,
Thinker and the Shade since the Golden Age.
Double Danger On Earth
Next up for the two Flashes was
Flash #129 (June, 1962) by
Gardner Fox,
Carmine Infantino and
Joe Giella, under another
Infantino/
Anderson cover.
This time around, Jay's Earth was menaced by a mysterious radiation coming from a comet that had crashed into the sun, with a meteorite in Arizona that was absorbing the radiation...but it vanished. Jay figured out it went to Barry's Earth, and quickly went there for help, but encountered
Captain Cold and
Trickster (who were both robbing the same location). So, Jay fought the villains, and quickly got help from Barry (as the Flash). The villains decided to team up s well, but were promptly defeated, with the Flashes taking the meteor back to Jay's Earth to coat the atmosphere to protect it from the radiation.
The JSA's last case (or at least the one readers saw),
All-Star Comics #57, was referenced in this issue, as was both
Jay and Barry's origins, as well as Barry's copy of
All-Star Comics #37 (the first appearance of the Injustice Society of the World).
Vengeance Of The Immortal Villain
Though mostly a team-up of Barry and Jay, the JSA returns in
Flash #137 (June, 1963) by
Gardner Fox,
Carmine Infantino and
Joe Giella, under an incredible
Infantino/
Anderson cover.
Barry sees problems in cities that seem familiar.....the cities on his Earth that are having problems are the homes of JSA members (heroes from Jay's Earth). A quick jump to that Earth finds trouble, as Jay suspects someone has captured the JSA. The two start to leave Keystone City to investigate, when Jay is captured in a stasis cube. Barry frees Jay from a stasis cube, and after being manipulated into fighting each other by Vandal Savage (the villain who captured the team), the two Flashes defeat the immortal villain, freeing the other Justice Society members, who decide that they need to meet more regularly in the future.
This story has the first appearances of the JSA's
Green Lantern,
Hawkman,
Atom, Dr. Mid-Nite,
Johnny Thunder and Wonder Woman, as well as
Vandal Savage .
Invader From A Dark Dimension
This is the first solo team up of Barry and Jay,
Flash #151 (March, 1965) by
Gardner Fox,
Carmine Infantino and
Joe Giella, under an
Infantino/
Anderson cover, since the JLA and JSA met.
Barry Allen faces a new menace, a black goop that Iris finds in a jewelry store (which keeps the Flash busy, and allows the store to be robbed). Similar thefts keep happening all over Central City, while, on Earth-2, Jay finds his foe, the Shade, with plenty of money to burn. The Shade was using his powers to rob on Earth-1, then take the loot to Earth-2, and the Shade traps Jay in darkness after Jay confronts him. Barry covers himself in gold on Earth-1, so Shade takes him as "loot", and, inside the dark dimension Shade accesses, Barry defeats the Shade, using his cane to free Jay and return the stolen goods.
This is the first time Barry and Jay's Earths are referred to as Earth-1 and Earth-2 in a Flash comic book, after their being named in the
first JLA/JSA team-up. Jay appears here between the second and third JLA/JSA team-ups.
Solomon Grundy Goes On A Rampage
A team up of two JSAers happens in
Showcase #55 (March-April, 1965) by
Gardner Fox and
Murphy Anderson (with cover by
Anderson), as Dr. Fate and Hourman team-up to save the original Green Lantern from his foe, Solomon Grundy.
Solomon Grundy ends up back on Earth, after the globe Green Lantern (Alan Scott) created crashes to Earth thanks to striking a comet. Grundy heads to home, Slaughter Swamp. Dr. Fate has a mystic alarm go off, which puts him on Grundy's tale, as Hourman gets involved as his chemical plant is close to Slaughter Swamp. Grundy fights the two, countering their magic and miraclo powers, escaping from them. Grundy then faces Green Lantern, and beats him, taking the original emerald crusader back to Slaughter Swamp, changing him into a Grundy like monster. Dr. Fate cures Green Lantern with his magic, and using their combined magical might, capture Grundy in a new sphere.
This issue recaps
Solomon Grundy's origin and battle with the JSA from
All-Star Comics #33 (as will as being his first appearance since the Golden Age), but how Grundy got back in that prison is recounted as part of the origin of the
All-Star Squadron, and Grundy returns soon, in the fourth JLA/JSA meeting. It is also the first appearance of Inza Nelson, Kent's wife (with their marriage being revealed first here; as she was just Inza Cramer when she worked with Dr. Fate in the Golden Age).
Perils Of The Psycho-Pirate
Next up is a story by
Gardner Fox and
Murphy Anderson (under a cover by
Anderson) from
Showcase #56 (May-June, 1965), with Dr. Fate and Hourman facing a new villain with a familiar name.
Archeologist Kent Nelson finds a set of Medusa Masks on a dig, and financier Rex Tyler finds his fiancee, Wendi Harris, fascinated by them (so much so she tries to steal them when displaying them at a party she held). Roger Hayden manipulated her into doing that, as he planned on taking the masks to take over the identity of Psycho-Pirate. Hayden was a cellmate of the original Psycho-Pirate (Charley Halstead), who taught him how to manipulate emotions and about the masks. The new Psycho-Pirate sets Dr. Fate and Hourman against each other until they are able to defeat him.
This issue has the first Silver Age appearance of the original Psycho-Pirate, as well as the reporting of his death. Dr. Fate appears here between the second and third JLA/JSA team-ups, and Hourman between the first and fifth.
Secret Origin Of The Guardians
Green Lantern #40 (October, 1965) is a big issue, revealing much of the origins of the DC Universe in this story by
John Broome,
Gil Kane and
Sid Greene, all under a great cover by
Gil Kane and
Murphy Anderson.
This story stars with a reunion of Alan Scott and Doiby Dickles at Gotham Broadcasting, with Alan having to ring-sling as Green Lantern to stop a meteor, which his ring seems to have no effect on, then to save Doiby from a falling tree, which oddly works as Alan's ring usually doesn't against wood. Alan goes to show Hal his new trick....which now doesn't work. Alan explains, with the help of his ring, that the comet was really an ancient Oan scientist named Krona, that ended up being freed from his prison by exposure to Alan's magical based ring.
Krona was an Oan scientist, long ago, who performed experiments trying to find the origins of the universe. He succeeded slightly, seeing a "cosmic hand" of creation (but his activities were also destructive, causing evil to be unleashed in the universe, and later, more trouble like the creation of the Multiverse, according to the Crisis on Infinite Earths). So, the Oans banished him in comet form (and eventually became the Guardians of the Universe, who formed the Green Lantern Corps).
Krona planned on doing more experiments, and was possessing Alan Scott's body (with Alan hiding in Hal's mind). The two battled, with Hal winning (as he had secretly switching rings with Alan, exchanging a weakness for yellow for one for wood), allowing Hal to defeat Krona, with the Guardians of the Universe returning Krona to comet form, the Green Lanterns swapping rings back, and Alan heading back to Earth-2.
This issue is the first appearance of the "Cosmic Hand", hinting at the foundation of the DC Universe (and Multiverse, all revealed during the
Crisis on Infinite Earths), as well as Krona's first appearance, and the first appearance of Doiby Dickles, Alan Green Lantern's Golden Age partner. Green Lantern Alan Scott appears here after his appearance in the third JLA/JSA team-up, and appears next in another team-up with Green Lantern Hal Jordan.
Mastermind Of Menaces
Another focus on a team-up of two JSA members,
Brave and the Bold #61 (August-September, 1965) by
Gardner Fox and
Murphy Anderson (under a stunning
Anderson cover), sees the gathering of Starman and Black Canary!
Ted Knight (Starman) is visiting Park City, and drops by the florist shop that is owned by Dinah Drake Lance, the Black Canary. Larry Lance knows there is a rash of robberies in the town, traceable back to Dinah's flower shop. Investigating, Starman finds that his old foe, the intangible Mist is behind it, having hypnosis, but Starman has problems working his Cosmic Rod near the Mist's men (due to frequencies given off by Mist's hypnotic flowers). Working together, Starman and Black Canary are able to defeat the Mist and his men.
This issue sees
the Mist return from the Golden Age, as well as Larry Lance (a detective who was friends with Black Canary, and is now revealed to be her husband). Black Canary and Starman were both last in the second JLA/JSA team-up, and appear next in the next issue of B&B (which is reprinted in the second volume of this Crisis collection).
The Hour Hourman Died
The last story in this collection is from
Spectre #7 (November-December, 1968) by
Gardner Fox,
Dick Dillin and
Sid Greene, and is a back-up story featuring Hourman in a bit of a problem.
Returning to his HQ under Tyler Chemical Company from a JSA meeting, Hourman encounters Tricky Dick Arnold, a thief phasing through the door. Taking a Miraclo pill for an hour of power, Hourman faces him, but the thief hits him with a beam from his Metalizer....which seems to kill Hourman! Normally only working against metal (allowing Arnold to phase through items to thief), that unique radiation seem to spell doom for Hourman....except his Miraclo was keeping him alive for one last hour. Tracking down the thief and analyzing the Metalizer, allowed Hourman to make an antidote before he faced his last hour.
Hourman appears here between the sixth and eighth JLA/JSA team ups.
All these stories are reprinted in the
Crisis On Multiple Earths the Team-Ups Volume 1, with a cover by
Jerry Ordway.
More JLA/JSA collections, including a second one of team-ups with team members will be forthcoming, as these meetings of members of teams from Earth-1 and Earth-2 foreshadow the
Crisis On Infinite Earths.
Wizard (William Asmodeus Zard)
All-Flash #12 (Fall 1943): 
Sportsmaster (Crusher Crock)
Huntress (Paula Brooks)
Harlequin (Molly Mayne)
All-American Comics #93 (January 1948): 
Thinker (Clifford DeVoe)
