Not long before World War I, HMS Dreadnought, a battleship that made all existing vessels obsolete, was launched at Portsmouth in the presence of the King-Emperor Edward VII. Fire-breathing patriots soon took up the cry, "We want eight and we won't wait.”

Winston Churchill, then a young home secretary in a government committed to spending more on welfare, wryly noted of the popular clamor for a naval race with Germany: "The Admiralty had demanded six ships; the economists offered four; and we finally compromised on eight.”

British debates about defense spending follow a familiar trajectory, although this time it’s politicians, rather than civilians, insisting that more should be spent on firepower. A military revolution in warfare is under way, too. Drones, off-the-shelf technology far cheaper than dreadnoughts, are being deployed to lethal effect on the battlefields of Ukraine and further afield — the daring "Spider Web" raid recently destroyed as much as a third of Russia’s strategic bombing force based thousands of miles away from Europe.