At the end of the French and Napoleonic wars, British sea-power was at its apogee. But by 1840, as one contemporary commentator put it, the Admiralty was full of ‘intellects becalmed in the smoke of Trafalgar’. How the Royal Navy reformed and reinvigorated itself in the course of the C19th is just one thread in this magnificent book which refuses to accept standard assumptions and analyses. All the great actions are here, from Navarino in 1827 (won by a daringly disobedient Admiral Codrington) to Jutland, D-Day, the Battle of the Atlantic and the battles in the Pacific in 1944/45 in concert with the US Navy. The development and strategic significance of submarine and navy air forces is superbly described, as are the rapid evolution of ships (from classic Nelsonic type, to hybrid steam/sail ships, then armour-clad and the fully armoured Dreadnoughts and beyond) and weapons. Rodger sets all this in the essential context of politics and geo-strategy. The character and importance of leading admirals – Beatty, Fisher, Cunningham – is assessed, together with the roles of other less famous but no less consequential figures. Naval specialists will find much that is new here, and will be invigorated by the originality of Rodger’s judgements; but everyone who is interested in the one of the central threads in British history will find it exceptionally rewarding.