[1][2] In 1916, Pundzevičius was mobilized into the Imperial Russian Army and after graduating from the Orenburg School for Praporshchiks he fought in the Northern Front of the World War I.

[1][2] Following his return to Lithuania, Pundzevičius was mobilized into the Lithuanian Armed Forces on 4 July 1919 and was appointed adjutant of the First Division Headquarters.

[1][2] 1921, Pundzevičius was appointed Chief of Staff of the Fourth Infantry Regiment in Alytus, and on 25 June 1921 he was promoted to the military rank of captain.

[1][2] In 1922, Pundzevičius graduated from the Higher Officers' Courses and was appointed Chief of the Third (Operations) Division of the General Staff.

[1][2] Upon graduating it in 1925, he was granted rights of an officer of the General Staff and was appointed commander of the Fifth Infantry Regiment.

[1][2] On 4 April 1939, he was appointed Chief of the General Staff, and multiple times temporarily served as Commander-in-Chief of the Lithuanian Armed Forces.

[7] It is unknown why Pundzevičius refused to become the Commander of the Lithuanian Armed Forces and gave up this position to Vitkauskas, who turned out to be pro-Soviet.

[7] On 1–2 October 1939, only one matter was discussed at the meeting of the Government of Lithuania – the demobilization of the Lithuanian Armed Forces.

[7] Following this meeting, the Soviet–Lithuanian Mutual Assistance Treaty was accepted and the military bases of the Red Army were established in Lithuania in exchange for the Lithuanian capital Vilnius.

[7] On 23 October 1939, Pundzevičius and some other high-ranking officers of the Lithuanian Armed Forces met the Soviet military delegation.

[7] On 15 June 1940, less than a few hours after the last meeting of the government, the Commander of the Lithuanian Armed Forces Vitkauskas issued the following order: "Brigadier general Kazys Musteikis has withdrawn.

[7] Then the Chief of Staff of the Lithuanian Armed Forces Pundzevičius issued an order that the Ninth Infantry Regiment must depart to help President Antanas Smetona to return.

For example, when Colonel Konstantinas Dulksnys, the Chief of the 2nd Division of the General Staff, was dismissed, major Korotkikh, a Soviet military attaché, arrived at the Army Headquarters and demanded that Major Parelis be appointed to replace the dismissed Colonel Dulksnys.

Following the Soviet occupation of Lithuania in June 1940, Pundzevičius served as Chief of Staff of the Lithuanian People's Army.

[10] On the same 24 June 1941, Pundzevičius was appointed Chief of the Lithuanian Armed Forces by the Provisional Government of Lithuania.