Uncanny X-Men #14-16: Who Could Have Predicted That AI Would Have Consequences?

This storyline is one I think really starts to make X-Men feel like X-Men. The introduction of the Sentinels and Master Mold. Before this the whole "a world that fears and hates them" was very background. They pretty much were just fighting other mutants. Introducing the Sentinels brings in that third major faction that has always been the hallmark of the franchise: All the bigoted humans. Anyway. Boliver Trask tells people that Mutants Bad and newspapers eat it up. Xavier decides to debate him on live television, and Trask pretty much says "it doesn't matter if you beat me in the debate, I have THESE" and pulls out Sentinels. Except immediately the Sentinels decide that humans are incapable of governing themselves and to protect them from the mutant menace they need to rule over them. A bunch of stuff happens. Heroes captured, Xavier saving the day with a Helicopter with a crystal hanging off of it, but in the end to stop the Sentinels from conquering everything Trask sacrifices himself to destroy Master Mold and end the threat.

X-tra Notes: The original Sentinels are much shorter than the ones everyone remembers (mostly from the cartoon). Also they are... hilariously dumb in selective ways. "Oh there are more enemies in the base, I don't have orders for what to do. Come with me so I can find my leader to ask him what to do!" Also, can't say I can completely argue with the "humans are too incompetent to rule themselves" assessment to be honest.