“And there came a day, a day unlike any other, when Earth's mightiest heroes and heroines found themselves united against a common threat. On that day, the Avengers were born—to fight the foes no single super hero could withstand!”

Each Friday Marvel.com will present a different column focusing on the one and only Avengers. From line-ups to costumes to villains to classic stories and beyond, we’ve got you covered on the history of Marvel’s most prolific team of heroes!

So let the call go out: Avengers Assemble!

By Jim Beard

With Avengers Vs. X-Men in full bloom, the history between the two teams becomes even more crucial to explore and understand. Their first meetings came about almost by accident, but they’ve lead to a rich series of epic battles and even greater teamwork.

Before looking at that first momentous encounter between the Avengers and the X-Men, one should follow the roots of that day to their beginning. Two stories stand as the preamble to that fateful first fight.

TALES OF SUSPENSE #49 tells of an atomic accident that drove the high-flying X-Man called the Angel to the brink of madness. Not in his right mind, the young mutant hero attacked none other than Iron Man, the Armored Avenger, and the two tussled until Angel’s true personality resurfaced. That lead to Iron Man being introduced to Professor X and the rest of the merry mutants, and a promise that the X-Men would be in his debt for his help.

Then, in AVENGERS #3, Iron Man used an experimental image projector to enlist the aid of the world’s heroes in finding the menace known as The Hulk. The Avenger contacted the X-Men, reminding them of their promise of aid, but the mutants possessed no news of the Green Goliath’s whereabouts and went back to their training session.

One year later, the real meeting between the full memberships of the Avengers and the X-Men finally came about in 1965’s X-MEN #9. It began with an order from Professor X for his students to come to the Balkans and carry on his mission should he fail. The crippled mutant leader approached the lair of Lucifer, the villain responsible for putting him in his wheelchair, but his foe awaited him with a dire scheme. If the Lucifer’s heart would stop, a gigantic thermal bomb would detonate and destroy the entire continent.

Enter the Avengers. Earth’s Mightiest Heroes arrived in the area tracking “evil emanations” by using Thor’s hammer as a kind of divining rod. Almost immediately, they ran headlong into the X-Men and, as these things go, trouble ensued. Despite Captain America’s urging for cooperation between the two teams, suspicions ran high and the teenage heroes were directed by the Professor to stop the Avengers at all costs. The fate of the world depended upon it.

So, a pitched battle broke out. The X-Men fired the first volley as Cyclops let loose with his optic eye beams and zapped Thor’s hammer out of his hand and into Iron Man, stunning the Golden Avenger. Cap tried to use his shield against Angel and Beast, but to no avail; thankfully Giant-Man loomed over the scene and swiftly intervened.

Then, it all broke down into individual bouts: Iceman iced up Hank Pym while Captain America tackled Cyclops and Thor braced himself for an assault by Angel. Iron Man zoomed in to put Iceman in the cooler only to find himself bounced by the Beast. The wondrous Wasp then spotted that “titian-haired tigress” called Marvel Girl and the subsequent cat fight devolved into hair-pulling and name-calling.

Deep below the ground, Professor X struggled against the machinations of Lucifer and managed to send his foe into mental oblivion. Contacting Thor through his incredible powers of the mind, the Professor explained the situation and the mighty God of Thunder quickly called a halt to the brouhaha. The epic first Avengers Vs. X-Men fight came to an end with no clear winners, but, with the Earth saved, no losers either.

The Avengers voted among themselves to allow the band of mutants to “deal with their foe in their own manner,” and left the battlefield with an eye toward the future. Among the X-Men, opinions remained divided on which team might’ve won the battle, but all agreed that when duty called, they should always stand ready to answer.