Twenty-seven-year-old George Lowther Steer was in Toledo, Spain, covering the civil war for London’s Times in fall 1936 when he was abruptly expelled from the city. The Nationalist military staff had discovered Steer’s recently published Caesar in Abyssinia, a book attacking its Italian fascist supporters. Steer explained how, among other sadistic measures, Benito Mussolini’s forces had used poison gas against Ethiopians, at most armed with antique weapons from past resistance against Italian invasion in 1896.

Following his stint in Ethiopia, at the time known as Abyssinia, Steer had a sojourn in London, signing on as a freelancer with the Times to complete his book. He remained in that position in Spain, where he headed after the war broke out in July 1936. Before he even reached Toledo, General Francisco Franco completed a savage, bloodstained attack. It was so devastating that his fellow generals named Franco the caudillo, unquestioned head of the rebel armed forces and their state.

Expelled from the city, Steer took a British Royal Navy destroyer to the Basque port city of Bilbao in January 1937. A few months later, on April 28, he published a bombshell story that horrified Europeans and Americans alike. Steer and a small group of foreign journalists had rushed to nearby Guernica after hearing that the historic town had been decimated on the afternoon of April 26 — a market day.

Many other reporters filed their stories the following morning. But as Nicholas Rankin explains in his 2003 biography, Telegram from Guernica, Steer’s story broke the explosive news that it had been the German Luftwaffe, specifically the Condor Legion, that had almost completely destroyed Guernica. Steer’s story ran on the front pages of newspapers around the world — rightly seeing the attack as a “dress rehearsal” for the global war that would follow.

The powerful armed forces of both Italy and Germany backed Spain’s rebel military forces against the democratically elected Republican government and the 35,000 committed volunteers it rallied from around the world. The Soviet Union would also offer limited aid and weapons. But the three largest democracies, Great Britain, France, and the United States, all declared neutrality, sitting out the Spanish War.

It was eventually discovered that Hermann Göring — Germany’s minister of aviation and war — saw Spain as an excellent training ground for the Luftwaffe, used to mastermind the blitzkrieg against Poland that followed three years later.

When artist Pablo Picasso read about the destruction of Guernica — and the way in which it happened — he became obsessed with creating an image of the desecrated town, known as “the cradle of Basque civilization.” On May 11, Picasso began work in his studio and by June 4 — working in record time — he produced the enormous, abstract black-and-white painting with its horrified women, terrified animals, and dead child.