By the beginning of the 20th century, Lipka Tatars had become so integrated into Polish society that they joined their Roman Catholic brethren in the mass migrations for the United States that gave rise to American Polonia, even founding their own mosque in Brooklyn, New York, which is still in use today. In 1919, at the outbreak of the Polish-Bolshevik War, two of the Tatar officers serving with the Polish Army Col. Maciej Bajraszewski and Capt. Dawid Janowicz-Czaiński started forming a Tatar cavalry regiment fighting alongside the Polish Army. This unit transformed into a squadron after the war, continued the traditions of Tatar military formations of the Polish-Lithuanian Commonwealth and became one of the most notable achievements of the Polish Tatar community in the 20th century. With the restoration of Polish independence, the Tatar community of Poland numbered around 6,000 people (according to the 1931 national census), mostly inhabiting the regions of Wilno, Nowogródek and Białystok Voivodeships. A large community of the Lipka Tatars remained outside of Polish borders, mostly in Lithuania and Belarus (especially in Minsk, the capital of the Belarusian SSR). Although small, the Tatar community formed one of the most vibrant national minorities of Poland. The Muslim Religious Association (est. 1917) focused on preserving the Muslim faith and religious beliefs. At the same time the Cultural and Educational Association of Polish Tatars worked on the preservation and strengthening of Tatar culture and traditions. In 1929 a Tatar National Museum was created in Wilno and in 1931 a Tatar National Archive was formed. All the Muslim people drafted into the army were sent to the Tatar Cavalry Squadron of the 13th Cavalry Regiment, which was allowed to use its own uniforms and banners. The Army Oath for Muslim soldiers was different from the one taken from soldiers of other denominations and was sworn in presence of Ali Ismail Woronowicz, the Chief Imam of the Polish Army.