The Bombing of Barcelona,

In March 1938, neighborhoods just like this one became the target of something the world had never seen before: a deliberate, continuous campaign of aerial bombing aimed not at soldiers or weapons, but at civilians going about their daily lives.

Mussolini ordered it without even telling Franco. His Aviazione Legionaria flew from Mallorca under Spanish colors to hide their identity, and between March 16 and 18, they struck 17 times in 44 hours, a fresh wave of bombers arriving every three hours, day and night. Nearly 1,000 people died, most of them in working-class neighborhoods.

The method was chillingly precise. Pilots cut their engines high above the city, gliding in silence over the rooftops. Residents heard the explosions before they knew planes were overhead. No radar, no warning system fast enough. British journalist John Langdon-Davies called it the "Silent Approach" and recognized what it meant: Barcelona was a laboratory.

Franco's fury when he found out had nothing to do with the dead. He was simply angry nobody told him.