armies "Poznań" and "Kraków". Mobilized in two groups. Because of fast German advance both groups entered combat separately and most units did not reach full mobilization. It consisted of 6 infantry divisions, 1 cavalry brigade and a battalion of tanks. Warszawa Army Created on September 10, 1939, from various units in Warsaw and Modlin Fortress area. Initially it consisted of approximately 25 infantry battalions and 40 tanks. Later it was reinforced by forces of Łódź Army and elements of Modlin Army. It was commanded by col. Walerian Czuma, although the nominal commander was gen. Juliusz Rómmel. Operational Groups Operational Group Wyszków Was one of the reserves of the northern front of Polish defences, created on September 1, 1939. According to Plan West, it was supposed to defend the line of the Narew river from Wehrmacht units advancing from East Prussia. Due to rapid German advance, the group withdrew towards the Bug river, and on September 11, Polish Commander in Chief Edward Rydz-Śmigły ordered General Wincenty Kowalski, commandant of Operational Group Wyszków, to merge his unit with Northern Front under General Stefan Dąb-Biernacki. It consisted of the following units: 1st Legions Infantry Division (Poland) (1 Dywizja Piechoty Legionów) from Wilno, 35th Infantry Division (35 Dywizja Piechoty – reserve), formed on September 7, 1939, out of units of the Border Defence Corps from northern parts of the Wilno Voivodeship, 41st Infantry Division (41 Dywizja Piechoty – reserve), formed in September 1939, out of units of the Border Defence Corps, Bartosz Glowacki (armoured train), elements of 2nd Regiment of Heavy Artillery. Independent Operational Group Narew Consisted of 2 infantry divisions and 2 cavalry brigades: 18th Infantry Division () from Łomża, 33rd Infantry Division ( – reserve), formed in late August 1939, out of Border Defence Corps units from the areas of Grodno and Wilno, Podlaska Cavalry Brigade () from Białystok, Suwalska Cavalry Brigade () from Suwałki and Grodno. Independent Operational Group Polesie Supporting forces Air support Lotnictwo Wojskowe (Polish Air Force) Naval and river support Polska Marynarka Wojenna (Polish Navy) See also Polish cavalry brigade order of battle Border Guard Fall Weiss (1939) History of Poland Invasion of Poland List of Polish armies in World War II Polish armaments 1939–45 Plan Wschod Soviet invasion of Poland World War II orders of battle Polish Land Forces Invasion of Poland