Abstract This study examines the social composition of the Greek Army from the War of Independence (1821–1829) to the conclusion of the Greek Civil War (1946–1949), exploring how class, regionalism, and ethnic diversity shaped its structure and function. While the Greek Army played a pivotal role in nation-building, its internal dynamics have often been overshadowed by political and military narratives. By analyzing recruitment patterns, training practices, and the experiences of soldiers, this research uncovers the army’s role as a microcosm of Greek society and a tool for social mobility. The study pays particular attention to regional disparities in recruitment, the integration (or exclusion) of ethnic minorities, and the evolving relationship between the army and the state. Using military archives, personal memoirs, and census data, it also investigates how the army reflected—and occasionally exacerbated—divisions within Greek society, especially during the National Schism (1914–1922) and the Civil War. By situating the Greek Army within broader European and Balkan military contexts, this research highlights its unique role in shaping Greek national identity. Ultimately, the study contributes to our understanding of how military institutions mediate social change and reinforces the importance of the common soldier in the making of modern Greece. Keywords: Greek Army, Social Composition, Nation-Building, Class and Regionalism, Ethnic Minorities, Modern Greek History