- Egypt's health ministry says 79 people were killed in Wednesday's clashes
- Matches between Cairo's top clubs, Al Ahly and Zamalek, have history of violence
- Anti-authoritarian fan groups of "Ultras" accused Mubarak regime of heavy handed treatment
- When revolution began, groups joined forces and led many of the Cairo protests
The deaths of more than 70 football fans shortly after a match between Cairo's Al Ahly club and the Al Masry club in Port Said, Egypt, shocked the world.
More than 1,000 more were injured in scenes that will leave an indelible mark on post-revolution Egypt -- because in Egypt soccer matters perhaps more than anywhere.
Passions have always run high in Egyptian football. The Cairo derby between Al Ahly and their rivals Zamalek is the biggest football match in Africa, and has to be held at a neutral venue, usually with a neutral foreign referee, to combat a history of enmity and violence.
In 2009, a World Cup qualifier between Egypt and Algeria sparked riots in Cairo, Algiers and beyond. But domestic football has also been on the frontline during the revolution that toppled former president Hosni Mubarak last year.
For the past five years, highly organized and anti-authoritarian fan groups of "Ultras," especially from Al Ahly and Zamalek, have been in conflict with the police at football grounds, objecting to the heavy handed treatment meted out to them by Mubarak's forces. In a country that had little public space, there were two forums for dissent: the mosque and the football stadium.
"The whole concept of any independent organization didn't exist, not unions, not political parties," explained the leader of the Al Ahly ultras last April.
"Then we started to organize football ultras ... to them it was the youth, in big numbers -- very smart people -- who could mobilize themselves quickly. They feared us."
When the revolution began, the groups joined forces and led many of the protests in Cairo's Tahrir Square. Some even credit the ultras with a major role in several of the key battles. But that hasn't endeared them to the authorities post revolution.
Since February, violence has continued to blight the game. The Egyptian Football Association even considered canceling last season's league.
Much of that was blamed on the security vacuum left when Mubarak's hated police force melted back in to the population. Although other people -- and many within Egypt's ruling Supreme Council of the Armed Forces [SCAF] -- view the ultras as the problem.
In that context, the deaths of 79 fans -- most if not all hailing from Al Ahly -- at a football match will leave many within Egypt questioning how and why this has happened as the police watched on.
SCAF has ordered the cancellation of the league as they deal with the worst civil disturbance to hit Egypt since the revolution. Al Ahly's fans announced three days of mourning and took to the streets to protest, demanding answers.
Wednesday's tragedy will reverberate far beyond the pitch.