Between my gobble gobble, I claimed this happened during a "Flashback" set near the conception of Xavier's dipshit son. Which was closer to World War 2 than the founding of the X-Men, but I didn't exaggerate how Marvel-Time is on a sliding scale, since most of the teenagers in the X-Men books have been teenagers for the last 30 years and brave Marvel keeps pace with real time in the real world, by pulling all the X-kids' birthdays consistently forward.
The book in question was
- ^ a b Uncanny X-Men #161, September 1981
For a synopsis on Uncanny 161, and a good look at the cover, consider following the link below...