The church bells had just struck four when the sky above Guernica began to scream.

The Bombing of Guernica: When Modern War Came to a Market Town

Three hours that changed the face of warfare forever

Nazi bombers tested terror-bombing tactics on a Basque market town, killing 1,600 and inspiring Picasso's masterpiece.

The church bells of Guernica had just struck four in the afternoon when María Ortueta heard the first drone of engines. It was Monday, April 27, 1937 — market day in this ancient Basque town, and the streets teemed with farmers, livestock, and families browsing stalls beneath the spring sun. Within minutes, the sky would turn black.

The Condor Legion arrived first — German He 111 bombers on loan to Franco's Nationalist forces, testing new theories of aerial warfare on a civilian population. Behind them came Italian SM.79s. They came in waves, methodically, for nearly three hours. High-explosive bombs shattered buildings; incendiaries turned the medieval center into an inferno. Junkers Ju 52s dropped their payloads while Heinkel He 51 fighters strafed terrified civilians fleeing into the surrounding fields.

Father Alberto Onaindía, a Basque priest who witnessed the attack, later testified: "The planes came low, like vultures... I saw an old man herding sheep, cut down by machine-gun fire. The sheep scattered across his body." His account, smuggled to the international press, would help expose the horror to the world.

Guernica held no military significance. Its small arms factory…

💡 The Condor Legion pilots received detailed questionnaires after the raid, treating Guernica as a clinical weapons test — their data directly informed Luftwaffe tactics used in World War II.