The Romanian Volunteer Corps in Russia (Romanian: Corpul Voluntarilor români din Rusia), or Volunteer Corps of Transylvanians-Bukovinians (Corpul Voluntarilor ardeleni-bucovineni, Corpul Voluntarilor transilvăneni și bucovineni), was a military formation of World War I, created from ethnic Romanian prisoners of war held by Russia. Officially established in February 1917, it comprised abjurers of the Austro-Hungarian Army, mainly contingents from Transylvania and Bukovina. These had been obliged to fight against Romania, and, once in Russian custody, volunteered for service against the Central Powers. As campaigners for self-determination and union with Romania, they passed political resolutions which, in both tone and scope, announced those adopted on Union Day 1918.