In May 1926, a coup took place in the Republic of Poland, which resulted in Józef Piłsudski, head of state (Naczelnik Państwa) in the period 1918–1922, taking over actual power in the country. Among other things, those three days in the streets of Warsaw stood out by the fact that during them Polish soldiers confronted each other: some military units partly supported President Stanisław Wojciechowski and the constitutional government of Wincent Witos, while others backed the plans of the first marshal of Poland, who could already boast a rather ‘whitewashed’ image among the population. Piłsudski’s plans were initially limited to the idea of forcing the resignation of the Cabinet, but finally turned into a broader campaign for the takeover of power, during which 379 people died and over 900 were wounded. The paper covers the sequence of events on 12–14 May, and focuses specifically on the role of army officers and units at different stages in the coup.