The history of naval warfare has often been overlooked within military history. Partly, this may reflect a general neglect of maritime history as part of history as a whole, a problem only recently drawing attention with the growing recognition of the importance of maritime connections in the patterns of global development. But partly, it reflects some truths about naval warfare. Naval warfare developed later than land warfare and long remained something of an adjunct to land warfare, acquiring semi-independent freedom of action only after 1500 ce. Indeed, most popular naval history focuses on the past two centuries and traces rapid technological development and the great naval battles of World War II. And yet, the close links between land and naval warfare, rather than justifying neglect of naval history, in fact point out the importance of considering it alongside the land warfare with which it often worked in tandem. Although we tell the story of naval warfare before the twentieth century in separate chapters, roughly one for each chronological part of this book, this is designed to highlight naval developments, not marginalize them. Given the key role of maritime activity in global developments noted above, separate naval chapters will also allow us to examine naval history in comparative and global perspective more readily.