|Eta was founded in 1959 to confront Franco's regime and promote Basque independence [EPA]
Euskadi Ta Askatasuna [Eta], the Basque separatist group, is marking the 50th anniversary of its foundation.
The group has been blamed for the deaths of more than 800 people during its violent campaign for the creation of an independent Basque state.
On the day Eta, the Basque separatist group, celebrated its 50th anniversary, others mourned.
The families of two Spanish civil guard officers, who were killed on Thursday, were joined for their funeral in Mallorca by several high officials, including Jose Luis Rodriguez Zapatero, Spain's prime minister.
The dead men, Carlos Saenz de Tejada Garcia, 28, and Diego Salva Lesaun, 27, were killed when their patrol car was blown up on the packed holiday island.
A day earlier, a massive car bomb ripped the front off a 14-story apartment building housing civil guards and their families in the historic northern city of Burgos.
Those asleep inside, including children, were lucky to suffer only minor injuries.
Here in Spain, no-one is in any doubt that this was the work of Eta and the country is now gripped by fear that this could mark the start of a sustained and bloody campaign.
Zapatero came to power in 2005 promising peace with Eta. He's not talking peace anymore.
"I want to condemn this new, low blow with much rage and pain, but also with much determination," he said in a televised address.
|Zapatero's socialist government shows little sign of acceding to Eta's demands [AFP]
"The criminal attack comes at a time when the civil guards and national police, with the co-operation of French security forces, are striking against the terrorist group as never before," the prime minister said.
"They have absolutely no chance of hiding. They cannot escape. They cannot avoid justice.
"They will be arrested. They will be sentenced. They will spend the rest of their lives in prison."
It is a refrain the Spanish people have heard before.
In recent months the government has claimed that Eta was irreparably weakened by a string of high profile arrests among its hierarchy.
But, as in the past, younger leaders appear to have stepped in to replace them.
It is among the younger of the group's members that the armed struggle still holds most sway.
They may be less experienced, but they are said to be more radical and more ruthless.
In the Basque city of San Sebastian, in the offices of Gara, a radical nationalist newspaper, I met Arnaldo Otegi.
He's the closest one gets to an Eta spokesman.
Otegi represents the collective Basque independence movement, some of whose political parties have been banned for refusing to condemn Eta violence.
|Carlos Saenz de Tejada Garcia and Diego Salva Lesaun are buried in Mallorca [AFP]
He refused to condemn this week's attacks.
"Events like yesterday in Burgos confirm the history of the past 50 years," he told me.
"Eta on one side, and the state on the other, locked in a cycle of permanent confrontation, with repression followed by response and no democratic solution in sight."
Eta describes the Spanish government as "fascist", a throwback to the days of dictatorship under General Franco, when the Basques were heavily oppressed.
It was at that time, in 1959, that the organisation was founded to confront the regime and promote Basque independence, that had last existed centuries ago.
Nine years later, in 1968, a frustrated Eta turned to violence to achieve its ends.
Since then over 820 people have been killed, hundreds of Eta members imprisoned, and sporadic negotiations have failed.
Eta insists the state carries out violence of its own, allegedly torturing prisoners, suppressing Basque nationalist politics, and denying the Basque people their freedom.
For its part, the government would argue the Basque region enjoys more autonomy than any other in Europe.
The regional Basque government controls taxes, policing, education and local media. It also has the widely-devolved powers common to all Spanish regions.
But that is not enough.
In the Pays Basque, across the border from San Sebastian in southwestern France, I visited the home of Julen Madariaga, a founding member of Eta.
Imprisoned in France in the 1980s, he claims no longer to be a part of the group, but still fiercely upholds the cause.
|Hundreds of people attend a rally against Eta in Azpeitia, in the Basque region [EPA]
However, he and others among Eta's old-guard are said to have realised that the use of violence has run its course, though his objection to its use is somewhat measured.
"A few years ago, I and others became opposed to the use of violence by Eta, not because of moral reasons but for political reasons," he says.
"From the early 1990s, Eta's use of violence as a weapon began to turn against the interests of the Basque people."
The violence, Madariaga sensed, was alienating fellow Basques.
Recent polls put public support for independence at around one-in-four.
What support Eta does enjoy seems to be among the radical youth - inflamed by what they see as hardline police tactics - and among families of hundreds of Eta prisoners held in jails across Spain.
They, along with the likes of Otegi and Madariaga, remain true to the goal: self-governance for the Basque regions of Spain and southwestern France.
And here, perhaps, is the central contradiction in Eta's method: the campaign of violence, among other things, seems to have diminished support for independence among Basques themselves to a very small minority.
Seen in that light, Eta's continued objective is hard to fathom.
Spain's socialist government shows little sign of acceding to their demands.
The last attempt to negotiate peace, in 2006, lasted only months and resulted in a resumption of the campaign of violence with a bombing of Madrid's airport that killed two people.
And, even if the Basques were to be offered independence, there doesn't seem to be much appetite for it among the population.
In the end, what seems likely is that there will be more Eta arrests, and 41 years of violence could yet be followed by many more.