In the wake of the German defeat, members of the People's Guard, the Polish military organization, joined by a number of volunteers—many of them veterans of the Great War—take up arms against the occupying German army in the major industrial city of Poznan.
At the beginning of World War I, close to three-quarters of Poland was under the control of Russia; the remainder of the country was ruled by Germany and Austria-Hungary. The start of war between Russia and the Central Powers, then, saw Poles fighting for both sides. With the downfall of the Russian Empire in March 1917, the Bolsheviks recognized Russian-held Poland's right to autonomy, and a provisional government was established in Paris. By later that year, however, Germany was in complete control of the country.
After the defeat of the Central Powers, the road to Polish statehood seemed to be clearing. A Polish republic was declared soon after the armistice, but the boundaries of the new state had not yet been set by the Treaty of Versailles. Germany was loath to cede any territory in defeat, and still considered much of the country, including Poznan and the surrounding areas, its property.
An incendiary speech by the well-known Polish pianist and politician Ignacy Paderewski and subsequent counteractions by the occupying German army may have sparked the beginning of the uprising on December 27, 1918. By January 15, the rebels had managed to take control of the city, taking advantage of the weakened state of the German army, which, like the entire German nation, was demoralized by defeat and distracted by growing internal conflict. On February 16, as part of the German-Allied ceasefire, France forced German recognition of the Polish army as an Allied force. The high command in Poznan subsequently submitted to the authority of the new Polish government, based in Warsaw.