After the fall of the uprising, the Russian garrison of Warsaw was significantly strengthened, while the Polish military units were disbanded. A new central military hospital was built next to what became the Park Ujazdowski and the castle became more of a barrack for the Russian military personnel. Around 1850 the outbuildings were again rebuilt by Jerzy Karol Völck, but were partially demolished 20 years afterwards. After the outbreak of World War I the building was again converted to a provisional hospital by the Russians. Captured by the German army in 1915, on April 10, 1917 it was transferred to the Polish Legions and became the main military hospital for Polish units fighting alongside the Central Powers (the more modern Ujazdów hospital located nearby remained a German-only hospital).