John Hopkins

Yet despite the bravery of such women, it is only early on that they fight in any real numbers.

Gender norms quickly reassert themselves, and soon women are encouraged away from the front lines and towards support roles or work in factories.

Rosa Sanchez becomes a telephonist and a postal worker.

But Mika Feldman not only represents an example of a woman fighting for the Republican side in the Civil War, she is also a foreigner.

And she's not the only one.

Because once Franco's forces reach Madrid and fighting begins in earnest in November 1936, the city becomes a symbol of the international struggle against right-wing authoritarianism.

The capital acts as a beacon for those with left-wing sympathies.

Those coming to its defense include the American writer Ernest Hemingway, who heads to Spain to report on the conflict.

Others, like the English novelist George Orwell, volunteer as soldiers.

These foreign fighters, over 35,000 of whom arrive in Spain over the course of the war, are formed into what are known as the International Brigades.

And while not everyone who fights in these brigades is a communist, what unites them is their anti-fascist ideology.

Thanks in part to the efforts of the international brigades, as well as the arrival of some fighter planes from the Soviets, Madrid stands firm for now.

As Franco's forces dig in for a prolonged siege, the Republicans begin to rebuild their forces.

And in early 1937, a couple of important defensive victories in the vicinity of the city, at Jaramja and Guadalajara, provide glimmers of hope.

Having been turned back from Madrid, General Franco decides instead to concentrate on other areas of government-held territory.

His forces begin to pick them off one by one.

He is assisted in this endeavor by an increase in military aid from Germany and Italy.

From the spring of 1937, the Luftwaffe's Condor Legion, alongside the Italian Aviazione Legionaria, carry out a shocking series of bombing campaigns against civilian populations in the Republican-held areas of the north.

It is the 26th of April, 1937.

In the dining room of the elegant Hotel Torontegui, in the northern Spanish city of Bilbao, a group of young men are enjoying a late dinner.