[3] With the start of the War of the Fifth Coalition, an Austrian corps under Archduke Ferdinand Karl Joseph of Austria-Este invaded the territory of the Duchy of Warsaw on 14 April 1809, engaging the Polish defenders soldiers under Prince Józef Poniatowski).

First a major attack on bridges in Warsaw's suburb of Praga by a 6,000-strong Austrian force which had crossed the river earlier was stopped by 1,000 Polish fortified defenders.

[3] A Polish administration and military formations were quickly organized on the taken territories, while generals Jan Henryk Dąbrowski and Józef Zajączek commanded the units slowing down the Austrians on the western bank of the Vistula.

[3][4] On 3 June, Russian forces also crossed the Austrian border to Galicia, trying to prevent the Poles from gaining too much strength and hoping to take some Austrian-held territories with no intent of returning them after the war.

[7] VII Armeekorps: Feldmarschall-Leutnant Archduke Ferdinand Karl Joseph of Austria-Este General Józef Poniatowski became a national hero in Poland following this campaign.

[10] In the aftermath of the Treaty of Schönbrunn, some of the territory liberated by Polish forces was returned to Austria, however West Galicia was incorporated into the Duchy of Warsaw.