stanislas saint clair was born in 1835 in his grandfather's mansion of vepriai, vilna governorate of the russian empire (now ukmergė district of lithuania). his father, alexander saint clair (1800–1880) was a former military officer from the british colonial army in british india and a scottish nobleman. his mother, pelagia kossakowska (1798–1881), was a polish-lithuanian noblewoman. his maternal grandfather was count jozef dominik kossakowski, one of the commanders in the november uprising against russian rule. his grandmother's name was ludwika zofia potocka. as of 1855, saint clair's family had sold their mansion in vepriai to podbereski family. brought up with strong polish identity of his family, he perceived struggle against tsarist russia as his patriotic duty and this led him to his balkan activities.