Poland was a major center of revolutionary fighting in the Russian Empire in 1905–1907, and the Łódź insurrection was a key incident in those events.

For months, workers in Łódź had been in a state of unrest, with several major strikes having taken place, which were forcibly suppressed by the Russian police and military.

Around 21–22 June, following clashes with the authorities in the previous days, angry workers began building barricades and assaulting police and military patrols.

[2][3][4] News of the 1905 Russian Revolution, together with its revolutionary spirit, spread quickly into Russian-controlled Poland from Saint Petersburg, where demonstrators had been massacred on 22 January.

Poland was a major center of revolutionary fighting in the Russian Empire in 1905–1907, and the Łódź insurrection was a key incident in those events.

[5] The wing of the Polish Socialist Party (Polska Partia Socjalistyczna, PPS) that was loyal to Józef Piłsudski believed that Poles should show their determination to regain independence through active, violent protests against the Russians.

[7][8] This view was not shared by Roman Dmowski's National Democratic Party (ND, Polish: endecja)[8] nor by the PPS's own "Left" (or "Young") wing.

[11] Piłsudski's PPS, while not planning for a major uprising then and there, had a policy of supporting the protest and harassing Russian forces.

[6][11] A larger group sent from Warsaw under Walery Sławek never made it in time to take control or affect the uprising; it was, in the end, an anarchic and unorganized violent protest against the Russian government.

[6] Tensions mounted further, and in the evening of 21[6][10] or 22 June[11] (sources vary), angry workers began building barricades and assaulting police and military patrols, killing those who did not surrender.

[11] Some of the heaviest fighting took place near the intersection of Wschodnia and Południowa (now Rewolucji 1905 r.) streets (where four barricades were located), near the Scheibler factory in the Źródliska park and on the Rokociny road (al.

[6] The PPS-supported worker factions found themselves facing not only Russian police and regular troops, but endecja militia.

Over the course of the "June Days", as the Łódź uprising became known in Poland, a miniature civil war raged between Piłsudski's PPS and Dmowski's endeks.