As an officer in the Lithuanian Army he participated in the Polish-Lithuanian war in the battles for Seinai, Augustavas and Varėna. For his accomplishments in the Lithuanian Wars of Independence in defending Lithuania from invaders, Plechavičius was awarded the highest military Order of Lithuania - the Order of Vytis Cross. He served in various cavalry squadrons and became the colonel of the Hussar regiment in 1922. Later he was the main officer behind the military coup of 1926, that removed the democratically elected government, assumed power and then handed it to Antanas Smetona.