Dimitrios Papatsonis participated in the Greek Revolution and played an important role in the Liberation of Kalamata on March 23, 1821, as the leader of a militant group of over a thousand Messenian fighters, including great chiefs such as Mitros Petrovas and  Panagiotis Kefalas. Later, he participated in the seizure of Kyparissia (26 March), which had been abandoned by the local Ottomans, and then he went along with other Greek rebels to Karytaina, one of the first strongholds of the revolution. In May 1821 he participated in the battle of Valtetsi and in July of the same year he was appointed one of the lieutenants of the Messenian forces that took part in the siege of Tripolitsa. During the fall of Tripolitsa, his men entered the city from the Mystras Gate, along with the men of Krevvatas, Giatrakos, Kefalas, and the bishop Theodoretos of Vresthena.