Prešov was the site of an ill-starred attempt in summer 1919 to set up a Slovak Soviet Republic hard on the heels of the Soviet Union's creation following the Russian Revolution of 1917.
Central Europe in general - and eastern Slovakia in particular - was in flux at the time. Hungary, defeated in World War I and recently stripped of more than half its former territory by the Treaty of Trianon, had been taken over by communist forces led by Béla Kun. They had already occupied Košice to the south, and were threatening Bratislava. Meanwhile, the forces of the newly-formed Czechoslovakia had moved to occupy the lands ceded to it under the new treaty: in the east (Podkarpatská Rus, now part of Ukraine) and the south (along the border with modern-day Hungary).
After Kun's forces took Košice in early June, the town hall balcony in Prešov was the scene for Czech journalist and communist leader Antonín Janoušek to proclaim the Slovak Soviet Republic on June 16, 1919.
Despite some initial sympathy with the aims of the putative revolution, local hackles were raised by the fact that the new republic's declarations were issued in the regional Sariš dialect and not Slovak. Slovak leaders and intellectuals, who might otherwise have been expected to back it, smelled a rat and argued that it was merely a front for Hungary to re-occupy the country (only the USSR and Hungary had recognised the new republic).
Nationalism trumped communism and the military and political tide soon turned against the revolutionaries: largely denied popular support, the republic collapsed after only three weeks, and by July 17 Hungarian forces had withdrawn from Slovak territory. Communists would have to wait another 29 years before their next stab at running the country.