This book started out as a conversation on a train journey from Cambridge (where we both then lived) to The National Archives at Kew. The conversations that have continued ever since – usually over copious amounts of tea, beer, wine, and Plymouth gin – have been the most enjoyable aspect of working on the book.

From the beginning we both agreed that there is a need for a maritime history of the civil wars of the 1640s, to provide students and scholars with an overview of this topic and to introduce it to a wider audience. We also agreed that any such history must take into account both the significance of the conflict at sea to the outcome of the wars and its place in long-term naval and maritime developments in Britain and Ireland. These have been the guiding principles we have followed in writing this book. Readers will decide for themselves whether we have succeeded.

Many other people have joined us in the conversations behind the book, and it is a pleasure to acknowledge them here. Our first and most important debt is to Dr David Smith, to whom this book is dedicated. David has mentored both of us, as Ph.D. supervisor to Richard and as a colleague of Elaine's on the New Edition of the Writings and Speeches of Oliver Cromwell project, and he has given endless and unstinting advice and encouragement. He commented on our first proposal for the book and read the full draft once it was complete. Our second major debt is to Peter Sowden, our editor at Boydell and Brewer, who responded enthusiastically to our initial idea and has continued to support us with the same enthusiasm and with no less patience. Without him this book would not have happened. We are also grateful to Dr J. D. Davies, Professor John Morrill, Professor Steve Murdoch, Dr Annaleigh Margey, and Dr Ismini Pells, who also read drafts and offered valuable comments; to Rachael Blakemore, whose copy-editing greatly improved the text, especially in harmonising two authorial styles; and to Cath D'Alton for preparing the maps.

Both of us have benefited greatly from our many colleagues and friends at the universities of Cambridge, Exeter, Oxford, Plymouth, and Reading.