A New Zealander contemporary of mine recently remarked during a conversation about politics: "The sea makes you free." It is a remark worth pondering, but it needs adjusting. Spain has plenty of seaboard, but historically not much freedom. Perhaps he should have said: "The ocean makes you free." The facts tend to support that. The great democracies are almost all oceanic.

It is not difficult to see why oceans make for freedom. They provide instant escape from oppressive government, and the means to bring home the wealth that puts oppressors in their place. England's absolute monarchs, from Elizabeth onwards, were always enmeshed in a delicate web of give-and-take with their seafarers. In 1776, George III found he had tried to take too much from his seafaring colonial subjects and fell into an oppressive war against them as a result. He lost. Part of the reason for Britain's defeat in what the Americans call the War of the Revolution was their superior sea power. Some of it was supplied by the French, but part was homegrown. A fascinating passage in this book by John Lehman, a former US secretary of the navy, is about American timber, which provided the Royal Navy with its masts from early in the18th century. After 1776, the supply was denied.

Retrospectively, it is ridiculous that two free peoples, the English and the Americans, should have fought each other twice, as they did in the 40 years up to 1812. But that was because of mismanaged politics, not strategy.

From a naval point of view, it may be argued that the affront felt by the Royal Navy's officers at defeat by the colonists was what provoked their do-or-die behavior during the wars of the French Revolution and Empire.

Between 1793 and 1815, the Royal Navy beat any French or Spanish fleet it met. Not so against the Americans in the war of 1812. In that tiresome little conflict, America's "heavy frigates", so called because American timber made possible their superior design and construction, beat their equivalents in a succession of fights. The war of 1812 laid the basis of the US Navy's battle-winning tradition.

Its self-esteem declined during the 19th century, when it ceased to be an oceanic navy. By 1917, when America entered the Great War, it was so again, and since that date has never looked back. In the inter-war years, it turned itself into a major medium of sea-borne air power, and in the great Pacific carrier battles of 1942-45 it reinvented the use of sea power as a strong arm of democracy.

So it remains. The 15 carrier-group navy, overseen by Lehman in his years as naval secretary, was a principal instrument of the West's victory in the Cold War, contributed greatly to the defeat of Iraq in the Gulf War and provided much of the air power to overwhelm the Taliban in Afghanistan.

This book, completed before September 11, contains a fascinating insight. The worst Islamic outrage to precede the attack on the twin towers was the destruction by truck bomb of a barracks in Beirut, which killed 241 US marines. After much dithering in the Pentagon, retribution was mounted by carrier-borne aircraft. A pilot fell into Arab hands and was eventually released, after much negotiation, to the Rev. Jesse Jackson. Only after his return were the battleships of the US Sixth Fleet allowed to fire their 16-inch guns into Arab positions. I was in Beirut at the time and saw the New Jersey openfire. The negotiator who secured the release of the pilot to Jesse Jackson was Donald Rumsfeld.

No doubt he remembered the effect of forthright retaliation even more clearly than I do. No doubt he also believed that totalitarian states should beware of tangling with oceanic democracies.

Click here to read an excerpt from On Seas of Glory