This thesis examines G.K. Chesterton’s poem Lepanto in relation to World War I. Chesterton wrote the poem in 1911, depicting the famous naval battle of Lepanto between the Christian-European Holy League and the Islamic Ottoman Empire that took place in 1571. The forces that Chesterton depicts in the poem can be seen as parallels to contemporary forces in Europe with an understanding of Europe’s position on the brink of war at the time of its writing in 1911. Examining books and journal articles that he was writing concurrently, we can see that Lepanto reflected Chesterton’s own political views. The poem Lepanto is especially significant not only for its depictions of Christian Europe’s internal and external threats, but for its strong emphasis on supernatural spiritual warfare corresponding to the human military action. Chesterton evokes Crusade imagery and stresses the impact of holy war in Lepanto, anticipating a similar situation in pre-WWI Europe. The thesis includes an examination of the historical battle of Lepanto, Chesterton’s understanding of war, and a commentary on the poem’s text.