In World War I he was mobilised into the Imperial Russian Army and graduated from the Peterhof Military School.

[2][clarification needed] In 1920, as a member of the Lithuanian Popular Peasants' Union, he was elected to the Constituent Assembly of Lithuania.

After that he attended the Institute of Technology in Zurich, Higher Officers' Courses in Kaunas, and the Royal Military Academy (Belgium).

[5] According to Victims of Communism Memorial Foundation, he was a primary source of the secret part of the Molotov–Ribbentrop Pact which he sent to the Latvian foreign minister Vilhelms Munters in 1939.

[3] In June 1944, he was arrested for sending a memorandum to Nazi officials asking to replace German authorities in Lithuania with a Lithuanian government.

[13] After a national debate and controversy, the city council led by the mayor Remigijus Šimašius voted to rename the alley in Vilnius to "Trispalvė" ("Tricolour", a reference to the flag of Lithuania) in July 2019.

[15] Škirpa received the following state awards and medals: https://www.academia.edu/36015959/Simonas_Jazavita_Illusion_and_Reality_of_Statehood_The_Search_for_Parallels_between_the_Lithuanian_Activist_Front_and_the_Organisation_of_Ukrainian_Nationalists |title=Simonas Jazavita - Illusion and Reality of Statehood: The Search for Parallels between the Lithuanian Activist Front and the Organisation of Ukrainian Nationalists | publisher=Taras Shevchenko National University of Kyiv |title=Simonas Jazavita - Kazys Škirpa's Geopolitical Vision of Lithuania and the Efforts to Implement it in 1938 - 1945.