'A Naval History of Britain' which begins in the 7th century has to explain what it means by Britain. My meaning is simply the British Isles as a whole, but not any particular nation or state or our own day... 'Britain' is not a perfect word for this purpose, but 'Britain and Ireland' would be both cumbersome and misleading, implying an equality of treatment which is not possible. Ireland and the Irish figure often in this book, but Irish naval history, in the sense of the history of Irish fleets, is largely a history of what might have been rather than what actually happened.

The arrival of the Barbary pirates radically changed English attitudes. Instead of patriotic pirates plundering foreign cargoes and bringing them homes to enrich their countrymen, the 'Turks' were in the usual Mediterranean business of slave-raiding - and now the English were the victims. The West Country men suffered the heaviest, and did not appreciate the irony. The Newfoundland fishery, dominated by Devon ports, lost at least 20 ships in 1611 alone.

Its subject is the slow and erratic process by which the peoples of the British Isles learnt - and then for long periods forgot - about the 'Safeguard of the Sea', as the 15th century phrase had it, meaning the use of the sea for national defence, and the defence of those who used the sea.

It is well known that we fight in God's cause... but unless God helps us by a miracle the English, who have faster and handier ships than ours, and many more long-range guns, and who know their advantage just as well as we do, will never close with us at all, but stand aloof and knock us to pieces with their culverins, without our being able to do them any serious hurt. So we are sailing against England in the confident hope of a miracle.

It is not surprising that only one medieval state, Venice, long possessed anything clearly identifiavble as a navy in this sense. We shall see that no state in the British Isles attained attained this level of sophistication before the 16th century, and no history of the Royal Navy, in any exact sense of the words, could legitimately begin much before then. This book, which does, is not an institutional history of the Royal Navy, but a history of naval warfare as an aspect of national history. All and any methods of fighting at sea, or using the sea for warlike purposes, are its concern.

The impossibility of keeping Englishmen sober ashore was a constant source of complaint, It was the great weakness of 16th century English infantrymen, whose performance when sober was admired even by the Spaniards. Already it was true, as it was to be for centuries, that many saw and despised the drunken sailor ashore, but few knew and admired him at his work afloat.

Medieval England was a great military power with a sophisticated machinery of government, but her naval administration, at best improvised and for long periods missing altogether, pointed to a grave weakness: the lack of any reliable means of putting a force of warships at the disposal of the crown. Only Richard I and Henry V of all the kings of England can be said to have understood the problem and attempted to remedy it. It is no coincidence that they wer by far the most successful in war.