Lepanto is not only one of G.K. Chesterton's finest poems, it is one of the finest poems in the English language. It is an intricate tapestry of images, an evocative telling of history, and a masterpiece of rhyme and rhythm and alliteration.
The battle of Lepanto was fought on Sunday, October 7, 1571, just south of the town of Lepanto (now Naupaktos), Greece, in the Gulf of Lepanto (Naupaktos), which adjoins the Gulf of Patras on the west and the Gulf of Corinth on the east. The battle was a key turning point in history. The Islamic forces under Selim II controlled the Mediterranean and were threatening to attack both Venice and Rome, which could have led to the collapse of Christian Europe. The poem brings out the fact that the odds are against Christendom in this monumental standoff. The Holy League will get no help from Germany, divided and weakened by the Protestant Reformation, or from England, under the self-absorbed "cold queen" Elizabeth I, or from France, under the worthless "shadow of the Valois," King Charles IX. But a surprise hero rises to the occasion, the "last knight of Europe," 24-year-old Don John of Austria, illegitimate son of Emperor Charles V, who miraculously leads the Christian forces to victory. (From the forward)
The book has not only the famous poem, but background information, explanations and commentary.