Well, technically. The Marvel Universe had technically already premiered in 1939, circa the same era that DC's Batman and Superman launched onto the scene. But what we know of as the Marvel Universe, a linked universe of characters and locales, it wasn't really a thing. The main Golden Age Heroes were linked together retroactively, with The Invaders in 1975 and, more recently, other series like The Twelve. There were series like All-Winner's Squad and the Young Allies, but there weren't concentrated on giving mainstays like Captain America another title. The closest to the modern superhero team was Young Allies, but as a group of teen heroes which fought the Axis, incorporating only two existing heroes, Bucky and Toro, fighting the Red Skull in the first issue (along with dialogue that is inarguably racist), it isn't reflective as what we got later on where heroes were not linked by the War, but by an urge to fight justice on American shores, coincidence and friendship; more modern comics have subverted how groups come together.
It's when The Fantastic Four began - and indeed subsequent heroes like the Incredible Hulk, Mighty Thor and Amazing Spider-Man that the Marvel Universe began to get complicated. For, it was not merely the united Allies in a 4-6 year war, but the whole of New York, each living in a shared, real-life city, in the early 1960s. As the Marvel Universe has grown far beyond that point - far beyond how Stan and Jack ever envisioned it - it's become increasingly confusing.
For, in the Marvel Universe, we have over 50 years of history, supposedly compressed into a 10-15 year timespan.
For, in the Marvel Universe, we have characters dying, resurrected, or left to unexplained leaps of logic and conjecture.
For, in the Marvel Universe, we also have Batman, the Transformers, the Doctor, HAL-9000, and even Sledge Hammer.
For, in the Marvel Universe, we also have Ultimate, Zombies, 1602, the movies, What If...?...
Making sense of all that? It's enough to give anyone an aneurysm. We don't see the Marvel Universe on a linear timeline, but lots of different timelines, and contradictions, and divergences, etc. It's placed on what we know as a 'sliding timescale.' Events may have initially occurred for the characters in the 1960s, but in the present day, their background is in the early 2000s. Events are compressed to make room for new events, retconned, or flat-out erased altogether.
Then where do we begin to chart it? It's impossible. Stories need to be considered individually. They may take basis from others also, but if anyone is to start, they must first look at a story on its own. The continuity it brings to the table, how characters are altered by their experiences, pop culture, etc.
Creating the timeline, there are a lot of things which need to be considered.
- Provenance: Information comes from a lot of different sources. We have Handbooks, writer's intent, Marvel's own intent and fan interpretation, even before we get to the issues themselves. Even in the issues themselves, there are different sources. Information to when a story is set or about characters is related in captions, first-hand dialogue, second-hand dialogue, the artwork, etc. Later issues may contradict earlier issues; often, the more recent issue will take precedence over an older one, however this isn't always the case.
- Real-World History: How does this story relate to what is going on in the present? A story is almost always in the present, when you're reading it. We're going to get stories revolving around Presidential Elections (e.g. the 2008 elections are an important part of The Death of Captain America), real-life figures, conflicts from Vietnam to the Gulf War to Iraq; there's even a 9/11 issue of The Amazing Spider-Man. Usually it will conform to these dates, but in the case of a contradiction, the comics are able to diverge from accepted history and create its own. After all, the Marvel Universe is not real life, though it tries to stay like it as much as possible, but the real world acts as a really useful guide as to when something takes place.
- Surrounding Issues: Other issues will undoubtedly affect when an issues occur. Closely knit events, like Secret Wars and Civil War, for example, brings lots of different strands and series in the Marvel Universe together, and therefore affects placement greatly.
- Pop Culture: We're going to get Ed Sullivan, Britney Spears, Rebecca Black, Star Wars etc. referenced in issue to help build up the world in relation to ours. Heck, sometimes these personalities appear in the story themselves. Let's not forget the story where Spider-Man teamed-up with Jay Leno.
- Costume Design: Character design has changed considerably over the decades, although often keeping the same basic style. Especially in flashback stories, the way costumes look are a good indicator of when something takes place. For example, Iron Man's Bleeding Edge armour was used between 2010 and 2012, so any time Tony Stark is shown wearing this armour, a story is likely to occur in this period. However, sometimes errors will crop up; the easiest solution is to just imagine the character is wearing a different costume than they are seen to be wearing in the issue, rather than attempting to create any sort of in-issue explanation. The same idea applies to topography, with both fictional and real-life buildings. Uncanny X-Men #191 saw the Statue of Liberty under restoration work, just as it was in 1984-86.
- Crossovers: Sometimes Marvel will link with other established properties, including licensed ones published by Marvel themselves. How much of an impact on continuity do they have? Is there an explanation as to why two completely different groups are together, or is it just arbitrary? In the case of crossovers, I only make note of stories relevant to the crossover - events referenced during the crossover, or later issues which reference the crossover. The third issue of The Transformers even featured Spider-Man: so obviously, this issue will be included, but maybe not the rest of the series, otherwise it just becomes a Transformers timeline rather than a Marvel timeline.
I've been working on this timeline for a long time. Right now I'm a sixth form student, but back when I started I was in Year 10. It's grown considerably since: it started as a small project, and has since gained hundreds and hundreds and hundreds of pages. I started with the Marvel movies: as a kid I saw the Spider-Man trilogy, and after that began to watch a few of the other films upon release: The Incredible Hulk, X-Men Origins: Wolverine, before things finally came to a head in 2011 when I saw both X-Men: First Class and Captain America: The First Avenger. The First Avenger left me hooked. I began reading up on Captain America in comics, beginning with Brubaker's Captain America and Bucky series; and the rest, they say, is history. Just like with the timeline, the collection has grown. I own hundreds of comics, have an entire shelf of graphic novels; Marvel Universe figures are smattered around, and I've caught up on most of the Marvel movies.
Primarily I'm a Marvel fan, but I read some DC - especially Batman - and I'm beginning to look into creator owned series as well (The Manhattan Projects, fuck yes.) I'm also into Doctor Who and Star Wars, but that doesn't really matter.
I'm intending to present the timeline on a weekly basis with a different theme. So, for the first week, I'll have a focus on the recently concluded Young Avengers by Kieron Gillen and Jamie McKelvie, looking at the continuity of all 15 issues. Later weeks will have focuses on different runs, characters, creators, etcetera. Expect at some point a look over of Ed Brubaker's run on Captain America and Winter Soldier, the Ultimate universe, Runaways, and classic storylines like The Dark Phoenix Saga.
There's a lot of content for me to cover, and I am never going to get through all of it: but it's worth a shot, right?