The more info that comes out about that huge brawl between Spanish soccer ultras that killed one participant, the crazier the whole ordeal seems. Apparently, the fight was pre-planned by the two ultras groups, and was intended to imitate the growing trend of "Russian-fights," where rival fans meet up for the express purpose of pummeling each other.
According to AS, members of Frente Atlético and Riazor Blues (the two groups involved in last Sunday's fight) saw videos like the one above, where Russian ultras get together in a secluded place and beat the shit out of each other, and thought, Wow, we need something like that!
So what is a "Russian-Fight"? AS has some answers:
In it, the contestants meet at an agreed place. Normally, the stage of the Russian-fight are vacant lots, parks or previously marked not very central streets. Each group arrives at one side of the previously established site and are fully separated from the other, as Frente and Riazor Blues did by the Manzanares. The use of knives is not allowed and the fight should be relegated to only punches, although it is true that most Russians wear gloves with reinforced knuckles. Punches and kicks anywhere on the body are allowed.
To differentiate, the sides agree on colors. Usually they will go with blue and the other in orange or red. It is also common that one of the groups takes off their shirts and fights bare-chested to clearly differentiate each other.
There are drivers of both teams (let us call them the match referees) to monitor the battle to make sure it is clean, that no weapons were used. They mark the beginning of the fight, usually with firecrackers or flares, as happened in Madrid. The fight ends when one group has been completely defeated, with their members on the ground or surrendered, or have surrendered or fled.
Hearing the rules is one thing; it's another to see one in action. Here's another Russian-fight, this time between Zenit and Spartak Moscow fans:
Here's another one between the same sides, this time in a field:
As AS mentions, these kinds of fights, originally popularized in early 2013, have spread to ultras groups around the continent. Here's a couple videos depicting Ukrainian hooligans duking it out:
There's an uncanny similarity to all of these fights, showing that this really is a thing. Europeans are fucking nuts.