Guernica is being obliterated again. The first and notorious time was on the afternoon of April 26, 1937, when, during the Spanish Civil War, the German air force obliged General Franco by bombing the market and strafing the feeing villagers. Today, Guernica is disappearing from guidebooks and road signs. Instead, its name is given in the Basque language as Gernika, over which its letter “k” casts a Nazi-like pall.

Gernika itself provides almost no visual reminder of that onslaught. During 30 years of fascism, no monument to the slaughtered was possible from the guilty gripping power. A no-specific peace memorial has been erected since, but even it stands well away from the town centre. Otherwise, Gernika is undistinguished by its property, a rural retreat from the ebullience and violence of Bilbao.

Gernika’s tourist attraction is its tree of liberty, a 2000-year old oak to which the Basques had linked their autonomy. The kings of Castile were expected to pay ritual homage there to Basque independence. Thus, the choice of Gernika as Franco’s target was intended to subjugate local existence.

Despite its reputation for horror, the Nazi attack on Gernika was slaughter on the small scale. A mere 29,000kg of bombs fell. Today, most individual bombs fell. Today, most individual bombs would carry that death load. In addition, only 1650 people died. The assumption is that “only” is a mark of what the Gernika raid heralded. Nowadays, collateral damage to no more than 1650 civilians during an air raid is no longer sufficient to inscribe a new word into our language. Rather, today’s mock headline might read “Small air raid in the Balkans. Only 1650 killed”.

Gernika’s significance did not come from the fascists’ killing of non-combatants. Wars have always involved a massacre of the innocents. At the start of this century, during the Boer Ear in South Africa, the British sought to break the resolve of the Boer fighters by herding their families into some of the world’s first concentration camps. Gernika was to break Republican morale in the port city of Bilbao. British bomber command adopted that Nazi aim by concentrating its attacks on the power civilian quarters of German cities.

Air power is what distinguished Gernika from previous attacks on the defenceless. In the aftermath of the firebombing of Dresden and Tokyo, the atomic bombing of Hiroshima and Nagasaki, carpet bombing across Indo-China and the fire-power televised during the (now first) Gulf War, we know to fear the fire that falls from the sky. But that form of terror was novel in 1937. Most of the peasants who were slaughtered that market day probably had never seen a fleet of aircraft before the civil war gave them a lesson in industrialised destruction.

Gernika’s best-known memorial has been Picasso’s painting which he did for the Spanish Republic’s pavilion at the 1937 exposition in Paris. Nonetheless, the Guernica canvas is remote from the specifics of the event with which it eventually became identified.

For many people, Picasso’s imagery has become synonymous with modern warfare. In truth, most of the picture’s elements are anachronistic. For example, instead of incendiary devices, he gave a broken sword from the classical sculpture. Picasso’s understanding of war was still back with that of Goya, whose paintings and etching of the Napoleonic campaigns could convey the disasters by focussing on had-to-hand combat between two or three people.

Picasso’s imagery is one-sided in as much as it is confined to the world of victims. Hence, he shows animals, domestic interiors and families. Absent are the aircraft from the Condor Legion. Not a propeller or a bomb is to be seen.

Picasso’s Guernica came closer to conveying certain practices of modern warfare through his use of only blacks, whites and greys. The result is that large sections of the canvas suggest the grubbiness of newsprint. Truth remains war’s first casualty. This century, the mass media have been the weapons for propounding the lies necessary for hatred. So outraged was world opinion by reports of the attack on Gernika that Franco pretended that the village had been dynamited by the retreating Republicans.

Picasso failed in his image-making because he, like any halfway decent human being, could not imagine how undefended civilians could be killed by fighters they never saw. In Vietnam, My Lai massacre became important because it turned attention away from the high-tech bombing to a human scale of cruelty.

The significance of Picasso’s Guernica lies in what he could not conceive. Even after endless slaughters, most of us cannot conceive the world the way the Pentagon does. Our residual humanness holds us back with the peasant in Picasso. We cannot imagine the annihilation of millions in a single air raid, still less a neutron bomb which kills people while preserving property.

In one sense, our failure incapacitates our resistance to the war machine because we can never entirely believe that our leaders could behave so monstrously, despite repeated proofs of their State terrorism. On the other hand, that reluctance to think beyond the personalised horrors depicted in Goya and Picasso is the root of a sanity which keeps us saying “no” to the warfare State.