This research examines how the Second Vatican Council (1962-1965) shaped the attitudes and pastoral responses of Catholic bishops during the Nigerian Civil War, also known as the Biafra War, a critical moment in both Nigerian and Catholic Church history. The war, triggered by post-independence instability, military coups, and the 1966 Igbo massacres, began with the secession of Biafra in 1967 and lasted until 1970. Amid the war, Catholic bishops faced the challenge of balancing ethnic loyalties with national unity, while navigating the broader implications of Vatican II. The Holy See, under Pope Paul VI, pursued diplomatic engagement, including a landmark meeting in Rome that brought together bishops from both sides, reflecting the Church's global commitment to peace and reconciliation. Given the proximity of the war to the close of Vatican II, this period provides a critical opportunity to assess how conciliar reforms, particularly those addressing peace, justice, collegiality, and the Church's role in modern society, were received and applied in a context of brutal war. The study explores how these teachings influenced episcopal actions, both individually and collectively. Drawing on secondary literature, archival materials, and oral histories, this research contributes to broader discussions on the role of the Church during times of crisis and the practical outworking of Vatican II in post-colonial Africa.