Adventure Comics vol.1 No.267 (December 1959)
“Serves him right, the criminal!”
In their second-ever appearance, the Legion returns to the 20th century not to praise Superboy, but to punish him. Having misinterpreted some frankly quotidian footage of the Boy of Steel destroying a bunch of things – I mean, even in the days before smartphone cameras and YouTube, every rube with a home movie camera must have caught footage of Superboy wrecking something for the greater good at some point – the trio of super-teenagers return from the future to lock Superboy away.
Lured to a planet initially designed as a shrine to Superboy’s accomplishments and populated by unnamed super-humans from some unidentified place or time – ostensibly they appear to be meant to be Legionnaires, but there are hundreds of them! – Superboy is imprisoned in a kryptonite cage by his former friends. To add insult to injury, they've been busy turning the town – including his foster parents and his own dog – against him.
It all works out in the end, of course, and Superboy seems perfectly pleased to see his fair-weather friends cheer for him, having been set straight.