In 1243, the village (spelled as Celad, and already having the status of a defensive gord) was mentioned again, this time in a document of Duke Konrad I of Masovia, as it had been destroyed in 1241, during the first Mongol invasion of Poland.[citation needed] In 1790, the Duchy of Siewierz was incorporated directly into the Polish–Lithuanian Commonwealth, and King Stanisław August Poniatowski made Czeladź a free city.During the January Uprising, in February 1863, Czeladź was briefly captured by Polish insurgents after their victory in the Battle of Sosnowiec nearby.Workers' settlements were built, and the dynamic growth was not stopped by World War I, when Czeladź was occupied by the German Empire.In 1915, a power plant was opened, and Czeladź became a magnet for farmers from overpopulated Lesser Poland's villages, who came here in search of work.[citation needed] Following the joint German-Soviet invasion of Poland, which started World War II in September 1939, the town was occupied by Germany until 1945.[10] In the mid-1970s, a number of blocks of flats was built in Czeladź, to accommodate an influx of workers employed at the construction of Katowice Steelworks.