On this day in 1936, Italian dictator Benito Mussolini gave a speech in Milan celebrating a new treaty of friendship with Germany and a political realignment of Italy. “This Berlin-Rome protocol is not a barrier, it is rather an axis around which all European States animated by a desire for peace may collaborate on troubles,” he said to a crowd of 250,000, flanked by a squad of Nazi officials. A transcription of his speech appeared in The New York Times the following day, along with a front page commentary that highlighted the axis comment.
That particular speech was important not just for introducing the term axis, but because it indicated a profound shift in Italy’s alignments in Europe. During World War I, Italy had been part of the Allies—Britain, France and Russia—and fought Austria-Hungary along its border. But in 1935, a decade into Mussolini’s stint as dictator, he invaded the east African kingdom of Abyssinia, present day Ethiopia. It was an attempt to show his muscle and turn Italy into an “empire.” The Italians quickly conquered Ethiopia, but the power grab had consequences. The League of Nations, the world body created in the wake of WWI, condemned the invasion and placed economic sanctions on Italy. The British were especially displeased because they considered East Africa their sphere of influence.
Feeling politically isolated from his country's old friends, Mussolini turned to neighboring countries for support, making overtures toward Hungary, Switzerland, Yugoslavia and Germany, then under the leadership of Adolf Hitler. Making nice with Italy was also in the interest of the Germans—having an ally along the south of Europe would give them a buffer for future attacks from that direction. After negotiating a friendship with Germany in October, on November 1, 1936, Mussolini stood in front of Milan’s cathedral and made their informal relationship official. That alliance became known as the Rome-Berlin Axis, named after Mussolini’s speech.
The two countries grew closer, and in May 1939, just a few months before Germany invaded Poland, they formalized their alliance with the Pact of Steel, a military and defensive agreement. In 1940, Japan joined the axis by signing onto the Tripartite Pact.
According to Today I Found Out it’s likely that Italy and Germany were referring to themselves as the Axis, at least unofficially, before the tripartate agreement. But it took longer for the term to catch on with the Allies. Kenneth Janda and Stefano Mula at The Chicago Tribune write that before the Tripartite Pact, a review of President Roosevelt’s public papers shows he never used the term "Axis." He uttered it the first time on November 11, 1940, then used it publicly at least 157 times during the course of the war.
After that, the terms Axis became standard usage when discussing the World War II coalition. Though Mussolini gets credit for popularizing the term in the context of the second world war, Janda and Mula say he actually cribbed it from the fascist premier of Hungary, Gyula Gombos, who wanted an “axis” of European power led by Germany that included Italy and Hungary as primary partners. Gombos, however, died in 1936, and Mussolini went ahead with the axis idea, with a slight edit, as his articulated version revolved around just Germany and Italy.