By Dominic Bailey
BBC News Online, Madrid
Spain has spoken with one voice, against terrorism and for peace.
Millions took to the streets in major cities across the country in a show of strength that many people have found hard to muster since the bomb attacks.
Huge crowds demonstrated their grief and anger across Spain
United, they found their voice and strength of spirit to send a clear message to the perpetrators.
Grey skies and drizzling rain followed the crisp winter's day on which about 200 died and more than 1,400 were injured or maimed in the Madrid attacks.
The weather on Friday reflected the mood of the capital where, throughout the day, Spaniards had paid their respects to the dead.
Cinemas and museums remained closed and shop owners, train staff and commuters stopped work for 15 minutes' silence at noon (1100 GMT).
Signs of sorrow
Hundreds of people visited makeshift shrines at the railway stations affected by the attacks.
Black ribbons were tied to cars, posted in windows and draped over flags on public buildings.
The marches for peace across the country were a show of solidarity on the first of three days of national mourning.
Two million took to the streets of Madrid, umbrellas sheltering them from the driving rain, but warmed by the community spirit that had brought them together with one purpose - to say "basta ya" [enough is enough] and "no to terrorism".
Workers, politicians, children students and the elderly marched together.
Chants of "murderers", "cowards" and "sons of bitches" rang out - mainly from the younger contingent - as well as the more traditional chants of "the people, together, will not be defeated".
"We're here to reject terrorism," said Nieves Azcarte, 41, who was accompanied by her 11-year-old son Luis Dussac. "What happened was an outrage. There are no words to express the barbarity of such an attack."
Luis' school teachers had had to explain to his class what had happened on Thursday.
"Those people had done nothing wrong but they suffered," he said.
Although no-one is sure who is behind the attacks, the chanting crowd vented their anger with only one group in mind - the Basque separatists Eta.
"Eta, listen, this is how we fight," they shouted.
In Madrid up to two million turned up despite winter weather
Open hands raised in the air, they added: "These are our arms. No to terrorism. We want peace."
"People feel impotent, they can't do anything," said student Fernando Manso. "They see it on television but don't know what to do. The march shows how people are feeling."
Politicians from all parties and some neighbouring countries led the march, but the protesters also had a message for them - that they could have done more to prevent the bloodshed. They whistled at government buildings as they slowly snaked past.
Although the reason for the march was a sombre one, and emotions were still very raw, the demonstration did have a lighter, communal sense of release and hope.
At the end of a dark couple of days of introspection and disbelief, it seemed that Madrilenos had, together, found the fire in their hearts that could not be extinguished by bombs or driving rain.