>>149731401It's one of the most fierce in Germany, but Hamburg's main rival is Bremen. Both clubs have been historic rivals fighting for supremacy in northern Germany since before WW2, the rivalry between the cities goes back to the Middle Ages.
St. Pauli is what it is now since about the early 80s, that's when the rivalry with HSV we know truly started. Not like they loved each other before that since they were city rivals, but especially between the first Bundesliga season and like 1985, both clubs had little to do with another: HSV was one of the biggest clubs in the country and never played St. Pauli. I've been told that a quite a few people even supported both clubs. With their new anarcho-leftie image change, St. Pauli began sharpening the rivalry with HSV, who had a few openly right-wing hool groups back then.
Things really kicked off in 2018, when HSV finally got relegated for the first time. Now both were in the same league. St. Pauli had closed the gap significantly. That's when HSV's attention had to shift a bit, less focused on Bremen and more focused on St. Pauli. Today, that rivalry is bigger and more emotional than ever. It's always been big for political reasons (HSV isn't right-wing by any means, but compared to and in the eyes of St. Pauli, everything is), but now it has become a somewhat regular sight with actual city supremacy on the line, even though HSV remains much bigger in most aspects. They've squandered their lead, so to say