If you don’t know already, I’m reading the entire Marvel continuity from Fantastic Four #1 onward. That’s approximately 745 issues up to the first appearance of Lorna Dane as related below.
In October 1968, in the Marvel Universe:
After defeating the Vulture, Spider-man is taken, unconscious, into police custody. While incarcerated, Capt. Stacy forbids that anyone remove his mask. Spidey gets caught up in a prison break and must save Capt. Stacy before he can make good his own escape. The Commies have stolen the plans to new Life Model Decoys from SHIELD and Captain America must face a robotic decoy of himself. Mar-vell must again aid the Earthlings as a dangerous solar being is brought to Earth and could destroy the entire planet. The Mandarin decides to try and control the Hulk, intending to start World War III. Nick Fury and Yuri Brevlov arrive to thwart Mandarin, but Hulk gets loose and, predictably, decides to smash everyone. Tiger-Shark follows Lady Dorma to Atlantis and forcibly takes the throne. Prince Namor returns and defeats Tiger-Shark, reclaiming the throne. One of the Mad Thinker’s leftover androids is activated and attacks Ben Grimm and Alicia. To save them, Ben must become the Thing again, an act that will make him the Thing permanently. The Crusher (Central American) escapes from Subterranea to seek revenge against Iron Man, who defeats him, but also jeopardizes his relationship with Jasper Sitwell, and likewise upsets the Maggia. Nick Fury is captured by Scorpio who steals his identity and puts Fury in the place of an LMD at SHIELD headquarters. The Brotherhood of Badoon secretly invades Earth and Silver Surfer, in his attempts to defeat them, inadvertently causes the public to think him a menace. Ultron-5 creates Vision to get his vengeance against the Avengers. Vision turns on Ultron and saves the Avengers. Captain Savage, back in WWII, and his men save Ben Grimm, who has been shot down over enemy territory. Daredevil dodges the police and ends up fighting the Jester on the Statue of Liberty, where he is drugged and captured. Hulk is transported into a punishment zone with Evil Inhumans. Maximus engineers Hulk’s escape, hoping to use Hulk to lead a revolt against Black Bolt and the rest of the Inhumans, but, as usual, Hulk decides to smash everyone instead. Mangog begins to unsheathe the Odinsword, but Thor calls a storm that awakens Odin from his Odinsleep. Ending Mangog’s people’s penance, he dissolves the creature and lets his former foes live in peace. A mutant named Mesmero begins to awaken latent mutants, an event which leads to the X-men running into a new mutant, Lorna Dane – who will soon be known as Polaris.
Best moment from October 1968:
It’s a tie. The first appearance of Vision is extremely significant, as is the return of Ultron (Avengers #57). But you can’t discount the end of the whole Ragnarok story arc that culminates with the dissolution of Mangog, after he bests every Asgardian and wrecks all of Asgard (Thor #157).