The one that started it all: the crossover before there were crossovers. Not a great artistic success, but a fantastic commercial one.
You can see where it fits into the larger timeline here.
Footnotes:
- The entirety of Secret Wars takes place between pages 2 & 3 of Thor #341. In #341, there were three whited out panels – panels which were provided the following month in the letter column of #342.
- These two sets of three issues all happen at around the same time.
- This story depicts an expanded version of the origin of Titania seen in Secret Wars #3.
- The vast majority of this issue takes place at this point.
- Takes place entirely within Secret Wars #4
- Appears to take place around the time of Secret Wars #6
- Jumps around a bit chronologically, but after Secret Wars #9 is the best fit.
- Takes place entirely within Secret Wars #10
- Iron Man returns with the Avengers.
- An epilogue, but probably the single best issue of the whole storyline.
- The Thing remained on Battleworld for 12 issues of his own title before returning to Earth.
- The Thing finally returned to Earth in this issue.