The Football War (La guerra del fútbol, in Spanish), also known as the Soccer War or 100 hour War, was a four-day war fought by El Salvador and Honduras in 1969. It was caused by political conflicts between Hondurans and Salvadorans, namely issues concerning immigration from El Salvador to Honduras. These existing tensions between the two countries coincided with the inflamed rioting during the second North American qualifying round of the 1970 FIFA World Cup. On 14 July 1969, the Salvadoran army launched an attack against Honduras. The Organization of American States negotiated a cease-fire which took effect on 20 July, with the Salvadoran troops withdrawn in early August.

Eleven years later the two nations signed a peace treaty on 30 October 1980.

Now that's hooliganism.

Football hooliganism is relatively new in Switzerland. One incident, dubbed the 2006 Basel Hooligan Incident, 13 May 2006, occurred on the last day of the 2005-06 season, when FC Zürich defeated FC Basel at St. Jakob Park to win the Swiss championship with a last-minute goal. After the final whistle, angry Basel hooligans stormed the field and attacked Zürich players. The Zürich team were forced to celebrate in the upper deck of the stands while the fighting continued. There was similar fighting in the streets that night.

No, it's all England's fault!!!!

The first instance of football violence is unknown, as many football games have been played around the world for years, but football and violence could be arbitrarily traced back to at least the 14th century in England. In 1314, Edward II banned football (which then was a violent free-for-all involving rival villages fly-hacking a pig's bladder across the local heath) because he believed the disorder surrounding matches might lead to social unrest or even treason. The first alleged recorded instances of football hooliganism in the modern game took place in the 1880s in England, a period when gangs of supporters would intimidate neighbourhoods, as well as attack referees and opposing supporters and players. In 1885, after Preston North End beat Aston Villa 5-0 in a friendly match, the two teams were pelted with stones; attacked with sticks, punched, kicked and spat at. One Preston player was beaten so severely that he lost consciousness. Press reports of the time described the fans as "howling roughs". The following year, Preston fans fought Queen's Park fans in a railway station; the first alleged instance of football hooliganism away from a match. In 1905, several Preston fans were tried for hooliganism, including a "drunk and disorderly" 70 year old woman, following their match against Blackburn Rovers.

Check out "Football hooliganism" on Wikipedia for more.