Issue: Journey into Mystery # 100
Writer: Stan Lee
Artist: Don Heck
Publication Date: January 1963
It's the conclusion to the two part Mr. Hyde showdown. It's also the one hundredth issue of Journey into Mystery, which one would think might involve a little more fanfare.
The ole secret identity works to Thor's disadvantage, as Jane still believes Don Blake is trapped, and that Hyde needs to escape in order to save him. So, she covers up Thor's hammer, which is akin to cutting Samson's hair, or at least giving him a trim. Fortunately, Thor recovers his hammer in time. Damage is done, though, as Odin sees this, and does not believe Jane Foster is worthy of becoming an immortal.
So, Hyde escapes, Thor is miserable, and Jane's not far behind. This is the melodrama Marvel comics thrive on. The villains don't win, but victory always comes at a price.
There is a backup story showing happier memories of Loki and Thor from their childhood. Or wait. Maybe not. Looks like Loki's always been a bit of a douche.
Stan's still working out the mechanics of how strong Mjolnir is. Here it bounces off the entrance to a sub. Not quite full strength yet.
Tales to Astonish # 51