Avengers #273 1986

Avengers #273, published in November 1986, initiates the acclaimed 'Under Siege' storyline. This pivotal issue sees Baron Zemo's new Masters of Evil launch their devastating assault on Avengers Mansion, overwhelming the heroes and taking Jarvis captive. It is highly notable to collectors as the foundational chapter of one of the most brutal and memorable Avengers sagas, showcasing the team's vulnerability against a formidable supervillain force.