Madrid train bombings: Simultaneous explosions on rush hour trains in Madrid, Spain, kill 192 people.

The 2004 Madrid train bombings (also known in Spain as the neuronym 11M) were a series of coordinated, nearly simultaneous bombings against the Cercanías commuter train system of Madrid, Spain, on the morning of 11 March 2004—three days before Spain's general elections. The explosions killed 193 people and injured around 2,000. The bombings constituted the deadliest terrorist attack carried out in the history of Spain and the deadliest in Europe since 1988. The official investigation by the Spanish judiciary found that the attacks were directed by Al-Qaeda in Iraq, allegedly as a reaction to Spain's involvement in the 2003 US-led invasion of Iraq. Although they had no role in the planning or implementation, the Spanish miners who sold the explosives to the terrorists were also arrested.Controversy regarding the handling and representation of the bombings by the government arose, with Spain's two main political parties — Spanish Socialist Workers' Party (PSOE) and Partido Popular (PP) — accusing each other of concealing or distorting evidence for electoral reasons. The bombings occurred three days before general elections in which incumbent José María Aznar's PP was defeated. Immediately after the bombing, leaders of the PP claimed evidence indicating the Basque separatist organization ETA (Euskadi Ta Askatasuna) was responsible for the bombings, while the opposition claimed that the PP was trying to prevent the public from knowing it had been an islamist attack, which would be interpreted as the direct result of Spain's involvement in Iraq, an unpopular war which the government had entered without the approval of the Spanish Parliament.Following the attacks, there were nationwide demonstrations and protests demanding that the government "tell the truth". The prevailing opinion of political analysts is that the Aznar administration lost the general elections as a result of the handling and representation of the terrorist attacks, rather than because of the bombings per se. Results published in The Review of Economics and Statistics by economist Jose G. Montalvo seem to suggest that indeed the bombings had important electoral impact (turning the electoral outcome against the incumbent People's Party and handing government over to the Socialist Party, PSOE).

After 21 months of investigation, judge Juan del Olmo tried Moroccan national Jamal Zougam, among several others, for his participation carrying out the attack. The September 2007 sentence established no known mastermind nor direct al-Qaeda link.