The 1650 to 1850 period was a time where seapower played an unprecedently unique role in the history of the world, one which arguably has never quite reached the same heights again. Long and lengthy wars of attrition were combined with, for the first time, the capability of ships to engage in systemic blockades, to cut off enemies from the growing world commercial system, placing them at a fundamental disadvantage in conflicts. In a world of rapidly increasing trade, exploration, and colonization, naval power represented a decisive tool, rendering command of the sea of unprecedented importance. Naval power would mobilize vast amounts of resources, in battles of economic endurance, where singular naval battles would be less important than operational and strategic capabilities of navies, War at Sea in the Age of Sail: 1650-1850 provides a strong overview of both the technical features of this period and a summary of some of the naval wars of the period. Although it has some biases and its choice of wars is inconsistent, its excellent technical side makes for a firm overall summary book.
The opening several chapters of the book deal with the technical and scientific aspects of navies, covering the strategic aspects of naval warfare (such as the difference between land-based monarchies with navies or the navies build by the commercial-maritime states) and its influence to begin with. Following from this is its discussion of the evolution of ship types, bases (and the different philosophies between nations, as the French for example preferred to surge ships into theater while the British built up permanent naval bases), design, armament, tactics, and social structures and life afloat.
After this it begins a chapter-by-chapter, war-by-war collection of the various naval wars of the period, starting with the Anglo-Dutch Wars, then Louis XIV's navy rapid rise and decline. These are generally a mixture of describing the navies involved, operations and strategy, and the battles which they fought. The Baltic campaigns between Sweden and Russia feature next, followed by a combination chapter of the War of Jenkin's Ear, the War of Austrian Succession, and the Seven Year's War. The American Revolutionary War, and the book's pinnacle, the Napoleonic Wars, succeed this, with a final chapter focusing on some of the activities of the Royal Navy after the end of the Napoleonic period, such as the Opium War with China or its intervention in the Eastern Crisis of 1840.
A very useful annex lists the battlefleet tonnage of the major navies.
The most definite strength of War at Sea in the Age of Sail is its good general technical descriptions of fleets and what their composition were, ranging from fleet units to specific ship types and how they evolved over time - such as how ships of the line gradually became bigger and their minimum size larger, or the disappearance of fireships from conventional naval tactics. Certainly, the descriptions are by no means exhaustive - but they're a good introduction into the subject and hold occasional surprise gems, such as the talk of the weaknesses of French cannons which does a good deal to explain some of the problems encountered by French ships in close range battles against British warships.
Excellent pictures, drawings, diagrams, and maps further match this. There are some great background pictures of ships or fleets to many pages, which make for wonderful accompaniment. While there are not many campaign maps, the maps which are given show where naval battles happened and thus help to show where they clustered. The technical drawings and illustrations are very good and interesting, ranging from anchors to cannons.
Some small errors riddle the book, such as claiming that the destruction of the French fleet at Vigo Bay in 1702 prevented the French from accessing trade with the Spanish Americas - belied by the constant shipment of silver regardless as well as French economic penetration of the Spanish Pacific colonies. It also has an inaccurate depiction of the French response to peace in 1748 - presenting the French as relieved that the war with the feared Royal Navy was over, instead of noting that the general popular opinion was that France had won great victories and been cheated of them by a foolish king. These mostly concern France - but it makes one wonder, what were other nations like? The lack of a real bibliography and footnote system makes checking claims hard.
There is also the question of what types of war were covered - there is next to nothing about the Mediterranean in the period, nor about the Ottoman-Russian wars, nor about the usage of the French navy in the War of Polish Succession, and piracy does not enter into the discussion either. Certainly, the principal conflicts are covered decently enough - but why does the relatively minor British naval actions in the Oriental Crisis of 1840 receive attention, while similar minor wars in the 18th century get no focus?
This hides a greater problem: that the book has, in that it quickly becomes a great paean to the Royal Navy, vaunting it greatly and embracing a triumphalist narrative of the British fleet as unbeatable and victorious. It is of course, somewhat grounded in reality: after all the Royal Navy did defeat the French fleet and proved to be vital to winning the Napoleonic Wars, but it is somewhat tiresome to have the same old story repeated over and over again. The clear adulation furnished on the Royal Navy is excessive.
\While certainly with many omissions, biases, and the occasional error, War at Sea in the Age of Sail still does a reasonably good job as a summary of the general era and even manages to cover some of the less well known conflicts, particularly the intervention of the British fleet in the Eastern Crisis in 1840, and shows that clearly the author has a sophisticated understanding of the era, such as his treatment of the reasons behind the French intervention in the American Revolution. It is not an indispensable book, but a good summary which is a fast read and a good introduction into the period and naval conflict, as well as helping to provide a general history to tie together the many disparate strains of history. This is somewhat less important these days with the widespread presence of online encyclopedias with decent general histories of their own, but the book still serves its purpose reasonably well, even if it could have been better.