This historical analysis of the political and religious relationship of Britain and Spain, from 12th-century dynastic alliances to the Spanish support of the English-American invasion of Iraq, asserts that there have been many significant links between the two countries over the past 800 years. While England and Spain were rivals in the New World, British and Spanish troops fought side by side for causes of mutual concern during the Peninsular War, Spanish Civil War, and World War II. This bittersweet relationship has been fundamental to Continental politics and the position of each country in the international realm.