The Madrid train bombings involved a sequence of meticulously planned attacks on packed commuter trains during the morning rush hour. On March 11, 2004, ten explosive devices were detonated across four train stations: Atocha, El Pozo, and Santa Eugenia, resulting in one of the deadliest acts of terrorism in European history. The bombs were hidden in backpacks and were detonated simultaneously, targeting trains filled with commuters heading to work. In total, 191 lives were lost, and more than 2,000 individuals were injured, some of whom sustained life-altering injuries.

The attacks were attributed to an al-Qaeda-inspired terrorist cell, which exploited the public's discontent with Spain's involvement in the Iraq war. They aimed to instigate fear and demonstrate the vulnerabilities of a nation at war, prompting debates on foreign policy and national security. The bombings were executed just days before the Spanish general election, leading to significant political fallout. After the attack, there was considerable national mourning, and Spain's political landscape shifted dramatically, affecting policies and public perception of terrorism.

In the aftermath, Spain, along with other countries, heightened security measures and engaged in a broader dialogue regarding terrorism and its root causes. The bombings not only impacted immediate victims but also reshaped public sentiment towards terrorism in Europe, influencing subsequent policies and approaches to national security across the continent.