Political leaders and royalty from Europe and beyond joined the people of Spain in a mass this morning to mourn the 190 victims of the suspected Islamist train bombers who struck Madrid earlier this month.
Military police ringed the Almudena Cathedral in the city centre and snipers took up position on rooftops as families of the dead and some the 1,900 wounded filed in to a congregation led by Spain's King Juan Carlos and a host of world leaders, including the Taoiseach, Mr Ahern.
Queen Sofia of Spain was just one of many seen to wipe away a tear as the choir sang a requiem for the dead. Outside, large crowds stood under leaden skies to watch images of the service on giant screen televisions in public squares.
The US Secretary of State Mr Colin Powell and the British Prime Minister Mr Tony Blair were the most prominent representatives of the coalition against Iraq, which Spain's outgoing Prime Minister Mr Jose Maria Aznar joined despite popular anger at home.
A group linked to Osama bin Laden's al Qaeda said the bombings of four commuter trains on March 11th were a reprisal for that war. Widespread irritation at his handling of the attacks may have cost Mr Aznar the general election three days later.
German Chancellor Mr Gerhard Schroeder and French President Mr Jacques Chirac, both strong opponents of the Iraq war, were among other world leaders attending, as was Prince Mulay of Morocco, brother of King Mohammed; some of those suspected of mounting the attacks belonged to Spain's big Moroccan community.
Mr Aznar's Socialist successor Mr Jose Luis Rodriguez Zapatero was present. He plans to pull Spain's 1,300 troops out of Iraq.
The congregation stood in prayer and sang hymns to remember those killed as priests recited plaintive chants.
Cardinal Antonio Maria Rouco Varela, the archbishop of Madrid, celebrated the memorial mass and sent a message of support to the families of the victims.
"Great is the pain that has overwhelmed your lives and those of your families since that black day in which brutal terrorist violence, executed with unspeakable cruelty, cut down the lives of your most loved ones," he said.
The mass also included a prayer for "the violent and the terrorists", urging them to "return to peaceful co-existence and never again attack the lives of anyone".