Medieval Europe was on a technological par with India and China, but within a century of the introduction of gunpowder Spanish ships had crossed the Atlantic. They discovered America. Galleons and galleys equipped with the first successful cannon came to dominate the seas. Some European countries became the first 'world powers'. John Guilmartin's beautifully written account explains how a country like Portugal was able to establish outposts from South America to India and the Pacific, how the Christian fleets wrested control of the Mediterranean from the Ottoman Empire and why King Philip's 'invincible armada' met with disaster during his attempt to invade England.