itold Pilecki was born May 13, 1901, in Olonets (Ołoniec) east of Lake Ladoga in Karelia, Russia, where his family had been forcibly resettled by Tsarist Russian authorities after the suppression of Poland's January Uprising of 1863–1864. His grandfather, Józef Pilecki, had spent seven years in exile in Siberia for his part in the rising. In 1910, Pilecki moved with his family to Wilno (Vilnius, Lithuania), where he completed Commercial School and joined the secret ZHP Scouts organization. In 1916, he moved to Orel, Russia, where he founded a local ZHP group.
During World War I, in 1918, Pilecki joined ZHP Scout section of the Polish self-defense units under General Władysław Wejtko in the Wilno area. When his sector of the front was overrun by the Bolsheviks, his unit for a time conducted partisan warfare behind enemy lines. Pilecki subsequently joined the regular Polish Army and took part in the Polish-Soviet War of 1919–1920, serving under Major Jerzy Dąbrowski. He fought in the Polish retreat from Kiev as part of a cavalry unit defending Grodno (in present-day Belarus). On August 5, 1920, he joined the 211th Uhlan Regiment and fought in the crucial Battle of Warsaw and at Rudniki Forest (Puszcza Rudnicka) and took part in the liberation of Wilno. He was twice awarded the Krzyż Walecznych (Cross of Valor) for gallantry.
After the Polish-Soviet War ended in 1921 with the Peace of Riga, Pilecki passed his high-school graduation exams (matura) in Wilno, and passed the exams for an NCO position in the Polish Army. He also studied at the Stefan Batory University in Wilno, and rebuilt his family estate, ruined during the war. He then took officer training courses. Assigned to cavalry regimen, in 1926, ensign, or the second lieutenant of the reserves; while in the reserves, he would subsequently actively support local paramilitary training activities. In the interbellum, he worked on his family's farm in the village of Sukurcze, and was known as a social work activist and an amateur painter. On April 7, 1931, he married Maria Pilecka (1906 – February 6, 2002), née Ostrowska. They had two children, born in Wilno: Andrzej (January 16, 1932) and Zofia (March 14, 1933). In 1938, he received the Silver Cross of Merit, for his involvement in the community and social work.