During its first two years of operation, the I-16 remained obscure to most of the world. The outbreak of the Spanish Civil War in 1936 quickly changed that.

When General Francisco Franco's fascist Nationalists challenged the government's Republican forces, the Soviet Union quickly came to their aid. Mussolini and Hitler wasted no time in supporting Franco.

At the beginning of the conflict, the superiority of Polikarpov's fighter plane surprised everyone. The Republican's I-16s demonstrated outstanding speed of climb in attacking enemy aircraft from above and below. Nationalists were instructed not to attack I-16s unless they had superior numbers.