Muslims are still supposed to follow the example of their Prophet. In his Life of the Messenger of God, the first and most important biography of Muhammad, Ibn Ishaq recounts what happened to the Jewish tribe known as the Banu Qurayza after a month-long siege: “Then the Banu Qurayza surrendered themselves and the Messenger confined them . . . Then the Messenger went out to the market of Medina—which is still the market today—and dug trenches in it. Then he sent for them and struck off their heads in those trenches as they were brought out to him in batches. . . There were 600 or 700 in all, though some put the figure as high as 800 or 900 . . . This went on until the Messenger made an end to them.” Does this scene remind one of anything? 

The contrast could not be clearer between the belligerent, even genocidal ethos of the Islamic State, and the repudiation by many in the West of the duty to fight even in defence of allies and victims of aggression. But there is a similar contrast with the Russians, who are much readier to take casualties than their Western counterparts. According to the Sunday Times, the estimated death toll in Ukraine is now at least 15,000, including more than 5,000 Russian conscripts, volunteers and mercenaries who have been killed in the last year, not counting casualties sustained by their Ukrainian separatist allies. By comparison, the total number of American, British and Coalition troops killed in both Iraq and Afghanistan over 15 years is just over 8,000. It is obviously wrong to sacrifice thousands of lives, civilians as well as soldiers, as Putin is doing, but so far there has been little sign of a backlash against the Russian president from his own people. On the contrary: they are apparently ready to die for him. As a Ukrainian woman told me recently in tones of disgust: “The Russians deserve Putin.” Perhaps life is held so cheap in Russia because life expectancy under Putin has declined to catastrophic levels, lower even than in Haiti. But do the Ukrainians and countless others (such as those on board the Malaysian airliner shot down by a Russian missile) deserve to be on the receiving end of a warlord who seemingly values human life so little?

So the West is up against at least two adversaries who are more warlike, more ruthless and more tenacious than we are. And there are plenty of others, from Iran to North Korea. What do we think will happen if it ever comes to a trial of strength?

We may not miss the military mentality; perhaps we would rather that boys memorised the vital statistics of actresses rather than warships. But at least the post-war generation knew what war was. Today, we are more likely to echo the internationalism of Einstein, who believed that if only the United Nations had a monopoly of nuclear weapons, then perpetual peace might be within our grasp, than Clausewitz, who taught us that, if an enemy is exerting force to compel us to do his will, then we are already at war.