Gernika - 75 years on

Around 4.30pm on April 26, 1937, a joint squadron of 23 German and Italian planes appeared in the skies over the historic, and undefended, Basque town of Gernika. Over the next five hours they would drop a total of 22 tons of high explosives and incendiary devices that would burn for days, destroying 70 percent of the town, and killing and wounding 1,600 people - around a third of the population.

Gernika became a powerful symbol of the atrocity of war. Unknown to the people of the town, they had been slated by General Franco and his fascist allies to become guinea pigs in an experiment designed to determine just what it would take to bomb a city into oblivion. Franco knew that the large number of outsiders attending the weekly market had swelled its population that day.

Three-quarters of a century later, the only survivors of the attack were children at the time, and they have carried the horror of what happened with them all their lives.

"I still get very emotional when I think about that afternoon," says Andone Bidagueren, who was aged eight at the time. "I can't help it."

The Civil War had broken out nine months earlier, and cities such as Madrid, Barcelona and Valencia had already been bombed. Rumors had already begun to spread that Gernika's famous marketplace might be a target. Andone says that his mother rose early that day, heading for the town to sell milk. Around 4pm, she returned home. While he helped her with the empty milk churns, they heard the sirens ring out.

"We all ran off in different directions. Of my six brothers and sisters, three of us headed for the river. We thought that it would be the safest place," he says. The three hid in the water long after the bombing stopped, returning home only after dark. They heard their parents calling for them. "If the planes come back, we'll all die together at home," Andone's father told them.

The planes dropped 22 tons of high explosives and incendiary devices

Andone stayed in the town after the bombing, meeting her future husband, the son of a baker, the next day. But many other residents fled to France, among them Javier Alberdi, aged nine, and Luis Iriondo, aged 14. They returned a year later after Franco's forces had occupied Gernika, and along with around 200 or so other survivors, have remained there ever since.

Others never returned to Gernika, such as Francisco García San Román, aged seven, and his two brothers, who moved to another town. But they will be in Gernika for the commemorations of the bombing.

Aware of the risk of bombing, the municipal authorities had built air-raid shelters, and stationed lookouts atop the hills surrounding the town. They were to signal to other lookouts in church towers, who would ring the bells in the event of an attack. These steps undoubtedly saved many lives.

"When we heard the alarm bells, my cousin and I ran into the woods covering the hills," says Javier Alberdi. "We didn't stop until we reached the hermitage of Santa Lucía, about a kilometer-and-a-half from the town. When the bombing stopped, we went to one of my aunts. About three hours later my mother arrived," His wife Estibaliz Bidaguren, then aged six, says she remembers little: "All I can remember is being very angry with my father - I blamed him," she says. "I was a little girl and I didn't understand anything."

As would happen 50 years later in the Balkans, when Serb forces targeted Sarajevo's library, Franco and the Germans deliberately set out to obliterate Gernika's identity by dropping incendiary bombs, which would destroy the city's cultural and historical identity.

Gernika is the cultural capital of the Basque people, the seat of their centuries-old independence and democratic ideals. It had no strategic value as a military target. A few years later, a secret report to Berlin was uncovered in which Von Richthofen, the World War I fighter ace who commanded the Condor Squadron that led the attack, said: "...the concentrated attack on Gernika was the greatest success," making the intent of the mission clear: it had been ordered on Franco's behalf to break the spirited Basque resistance to his Nationalist forces. Gernika had served as the testing ground for a new Nazi military tactic: carpet-bombing a civilian population to demoralize the enemy. This would be put to terrifyingly effective use two years later, when Hitler invaded Poland.

Franco knew that the weekly market had swelled Gernika's population that day

As part of the commemorations, a group of historians has set about locating and interviewing the survivors of the bombing. In 2010, the Gernika Gogoratuz association brought out a book that recorded the testimonies of some 22 survivors. Since then, eight have died.

Luis Iriondo was alone when the bombers struck. "I found a shelter in one of the four bunkers that had been built in the town square. I can't remember how many of us there were. It was dark and I could hardly breathe. We ended up lying down so as to get more air," he says.

This year, Andone Bidaguren will go to the local cemetery and lay flowers at the memorial built in 1995 to remember the victims of the bombing. "I tell my grandchildren that this is something we should never forget."

On April 24, 1999, 61 years after the attack, the German parliament formally apologized to the citizens of Gernika for the role the Condor Legion played in bombing the town. The German government also agreed to change the names of some German military barracks named after members of the Condor Legion. By contrast, no formal apology to the town has ever been offered by the Spanish state on behalf of the Franco regime that ordered the attack.