Your correct about the first group. They were formed to fight the Nazi's iirc and were forcibly disbanded after the Reich got started.
However (from Vox)
Antifa’s origin story begins in the 1930s, in two European countries: Germany and the United Kingdom.
In 1932, the Communist Party of Germany founded an organization dedicated to opposing the rise of fascism called Antifaschistische Aktion — abbreviated, at times, as antifa. The group engaged in a series of direct actions to challenge the Nazis, including street brawls, but were forcibly dissolved after Hitler’s rise to power.
The British experience was quite different. In 1936, the British Union of Fascists — a political movement with real electoral support, but not nearly as powerful as the 1932 Nazis — attempted to lead a march through London’s heavily Jewish East End. Thousands of Jews and left-wing activists attacked the fascists and their police escorts, raining homemade bombs and rocks down on the parade. The BUF forces retreated; the leftists celebrated victory in what’s now remembered as “the Battle of Cable Street.”
While Antifaschistische Aktion was too late to stop the Nazis with force, modern antifa sees the Battle of Cable Street as proof that fascist movements can be defeated before they gain popularity if they’re forcibly blocked from appearing in public. They call this “preemptive” or “anticipatory” self-defense: Since fascists want to use force against you eventually, you’re justified in using it first.
This interpretation could be true, but it’s certainly debatable. One could argue that street brawling
helped the Nazis more than it hurt them;
some evidence suggests that Cable Street led to anti-Semitic reprisals and made the British public more sympathetic to the BUF.
Regardless, this “violence works” historical narrative is at the core of antifa’s ideology today. They deeply believe that the different paths of Germany and Britain in the interwar period proved the need to confront fascism with force.
“Self-defense, which often entails violence, is an indispensable part of [antifa] politics,” says Mark Bray, a historian of antifa at Rutgers University. “They believe, and I think rightly so, that fascism and proximate far-right politics are inherently aggressive — and that, if you’re not ready to defend yourself in advance, it may be too late when the time comes.”
It’s probably not a coincidence that the modern incarnation of antifa also has its roots in the UK and Germany. This time, the crucial period is
the 1980s.
Back then, West Germany was dealing with a resurgence in neo-Nazi sentiment and activity. The punk rock scene in Britain, an aggressive subculture with anarchist political leanings, was similarly becoming a recruiting space for white nationalists tapping into anger and disaffection common among British punks. In both countries, activists took matters into their own hands — fighting neo-Nazis on the ground in order to prevent what they worried could be a replay of the 1930s.
One UK-based group, called Anti-Fascist Action in a direct nod to the 1930s German group, became the inspiration for a similar organization in American spaces. Called Anti-Racist Action, on the theory that this language makes more sense in an American political context, it became an organizing banner for punks (at first) who wanted to boot neo-Nazi skinheads from their own scene. In the 2000s and 2010s, the label Anti-Racist Action gave away to the now-popular antifa.
Stanislav Vysotsky, a sociologist at the University of Wisconsin Whitewater who has done extensive interviews with antifa members, describes them patrolling neighborhoods and guarding the doors at punk shows to prevent Nazis from entering. When these tactics fail, they resort to violence.
“Fascists are first aggressively confronted about their presence and ordered to leave by large group of people (in many cases, the entirety of the venue),” he writes in
a 2015 paper. “If fascists do not leave when confronted, force is often used to eject them from the space, either in the form of physical removal or through a violent clash between them and anti-fascists.”
Vysotsky sees this as a kind of “anarchist policing.” In the punk subculture, people don’t like or trust the police: Armed agents of the state are as un-punk as you can get. But neo-Nazi skinheads won’t leave concerts politely when told; some kind of counter-force is required to keep punk shows safe for people of color and Jews who want to attend. Hence, the need for loose groups of anti-fascists brawlers willing to kick them out.
Antifa might have remained little more than a facet of America’s marginal punk scene, unknown to the vast majority of Americans, if it weren’t for the rise of Donald Trump and the alt-right in 2015.
Trump’s victory was accompanied by the growth of a kind of more electorally minded white nationalist politics, an organized effort to win power and influence by riding the soon-to-be president’s coattails. This “alt-right,” personified by the supposedly “dapper” white nationalist Richard Spencer, organized online and staged increasingly public real-world demonstrations.
This is not something antifa could abide. Taking lessons from the forebears in the 1930s and 1980s, they started organizing to stop the modern far-right before it could really get started.
“As fascist and far-right movements and personalities publicly supported Trump’s campaign and presidency, antifascist opposition mobilized against them,” Vysotsky tells me. “These mobilizations became more commonplace after his inauguration as fascists organized rallies under the guise of support for Donald Trump and his agenda which were met with strong, sometimes violent opposition.”
As the alt-right became more prominent, so did their more radical left-wing opponents — a degree of notoriety that these “anarchist police” simply were not prepared for.
It's an interesting discussion, but again I think my point is a better one. It's anti-fascist, not communist or marxist.