4 of December 1830 r. the fortress was captured by insurgents and soon modernization works began under the supervision of Polish engineers, The destroyed bridge under Zegrze was rebuilt and access roads were built under Serock. After the capitulation of Warsaw, Modlin from 20 September to 9 October 1831 r. became the main defensive point of the Polish army. At that time, the defense of the fortress was commanded by Gen.. Ignacy Ledóchowski. Tsarist authorities in 1834 r. changed the name of the fortress to Nowogeorgijewsk and began a thorough modernization and expansion of Modlin (in years 1832-41) according to design. Eng. Ivan J. Put in A. Feldmana, erecting outer bastions and cannon posts consisting of 6 fronts. Gates were installed in the curtains of the internal perimeter, in the western curtain also the postern (underpass). In years 1832-40 the fortress housed a monument to Fr.. J. Poniatowski (currently in Warsaw in front of the president's palace). After the monument was handed over to Prince Iwan Paskiewicz, he was taken from here to Gomel, from where he returned to Warsaw in 1922 r. The fortress was expanded even after 1864 r. according to the indications of gen. Edward Todtleben. W 1878-80 Modlin was transformed into a fortress (ring). A ring has been built 8 forts: I'll step in, All that, Pomiechówek, Janowek, Oakwood, Małocice, Cybulice Małe and Grochale, by placing them at a distance 2-6 km from the fortress, and in years 1912-14 outer ring (10 forts in the distance 4,5 – 8 km from the citadel) on the perimeter close 50 km. Numerous field forts and suburbs protected the fortress against unexpected enemy attacks and covered the line of the Vistula railway line. Warsaw – Mlawa. W 1877 r. a two-level iron bridge was built on the Narew River (road mountain, railroad pit) wg proj. Eng. Stefan Zieliński. In years 1875-1900 An officers' settlement and a military casino were also built within the fortress. In August 1915 r. Modlin, despite the large Russian crew (more than 100000 soldiers, including 30 generals), stayed pretty fast (within 7 days) captured by the German army. In early November 1918 r. the German crew was disarmed by Polish soldiers. From 1919 r. Modlin has also become a port (Kazuń suburbia) for the newly established Vistula War Flotilla and a training center for seamen. In the interwar period, approx. 1600 seamen. Base in Modlin (then also in Toruń) with the yard, workshops, warehouses and a port was the base for the Polish navy. During the Polish-Bolshevik war in August 1920 r. in Modlin there was the headquarters of the commander of the 5th Army of the Polish Army, gen. Władysław Sikorski. 16 of August 1920 r. in the Modlin area there was a battle between Polish troops from the 5th army and the fortress under the command of Colonel. Edward Malewicz and the Bolshevik units of the 3rd army of commander IV.5. Lazarewicz. As a result of the fighting, Soviet troops were pushed towards Nasielsk. In the interwar period, the Cadet Corps was located outside the School of Maritime Specialists in Modlin. (from 1919 do 1926 r.), Sapper Training Center (from 1926 r.) and the Armored Weapons Training Center (from 1936 r.). Headquarters were stationed here 8 DP i 32 pp. During the defensive war 1939 r. Initially, Modlin was a base for the army of "Modlin”, and then he became famous for the heroic defense of the Polish crew under the command of, initially, Col.. W. Młodzianowski, then gen. brig. S. Małachowski, a 13-29 September 1939 r. gen. brig. Wiktor Thommće. About. 1700 Polish soldiers, were injured approx. 3000, a ok. 12 000 The Germans deported to the transit camps in Mława, Iłów and Działdowo.