Jan Jagmin-Sadowski (April 24, 1895 in Grójec – October 5, 1977 in Warsaw), was a general of the Polish Army, having served in World War I as a member of Józef Piłsudski's legions, as well as commanding Polish forces during the invasion of Poland in 1939.
Originally, their main settlements were in the area of Płock, Łomża, Wizna, Czersk, Ciechanów, Płońsk, Zakroczym and Grójec.