Conflict comes highly recommended. Two former chiefs of the defence staff, Generals David Richards and Nicholas Carter, praise it for identifying key lessons from the past appropriate to the future. A former MoD strategic adviser, Sir Hew Strachan, says it will ‘challenge the professional and enlighten the generalist’. The US marine corps general and former secretary of defense James Mattis, ‘the warrior monk’, says it is ‘a clear-sighted assessment of war’s future’. And the late Henry Kissinger called it ‘an exceptional book, written by two absolute masters of their profession’.

Kissinger had been General David Petraeus’s champion since the latter’s fall from grace as head of the CIA following the exposure of an affair in Afghanistan with a subordinate officer, the wife of a former officer. As a past national security adviser and secretary of state, he features large in the book. Air and naval endorsements are evidently yet to come.

‘It is important to establish what this book is not,’ say the authors: ‘It is not intended as a comprehensive history of all conflict since 1945’, impossible in a single volume. That said, other than the wars of kites or crows flocking and fighting in the air, it seems remarkably comprehensive. But although, the authors maintain, ‘strategic concepts have evolved faster since the second world war than at any comparable period in history’, still the Prussian general and military philosopher Carl von Clausewitz gets prime billing, quoted as early as the fourth paragraph: ‘Warfare [is] politics by other means.’

Clearly the authors know what Clausewitz meant, as evidenced by what follows in the book, but this is not an entirely faithful rendering of ‘Der Krieg ist eine blosse Fortsetzung der Politik mit anderen Mitteln’. The first publication in English (1873) of Clausewitz’s On War, by Colonel James Graham, translated ‘[War is simply a continuation of politics] mit anderen Mitteln’ not as ‘with [the admixture of] other means’, but ‘by other means’, allowing the inference that politics ends where war begins. Nothing could be further from the truth, in ‘rational’ war at least. (There are other types of war, for example those characterised by Anatol Rapoport as ‘cathartic’, and ‘cataclysmic’.) Georges Clemenceau, the prime minister of France from 1917, reclaimed Clausewitz’s real meaning when he said: ‘La guerre! C’est une chose trop grave pour la confier à des militaires.’ The apparent paradox was probably meant for impact. Had he said ‘la stratégie’ rather than ‘la guerre’, no one would have batted an eyelid.

The dynamic of the military vs the political in strategy has indeed been a constant in war since at least 1648, and in many ways it is one of the most interesting aspects of Conflict. Thus, perhaps, General Richards says he hopes ‘our leadership will take time to read it’. If pressed for time, our political and military leadership would do well to read the salutary introduction and first chapter, ‘The Death of the Dream of Peace’, and in particular the section on the Korean War, subtitled ‘Getting the big strategic idea right’. General Douglas MacArthur, one of the towering heroes and egos of the second world war, ‘ultimately got the big strategic idea for the conflict wrong, thus failing in the first and most important task of the strategic leader’.

MacArthur’s big idea was that the invading North Korean army could be pushed back and destroyed by superior US firepower, and that if China sent an army into North Korea, he could destroy that too (if necessary with nuclear weapons). That he conducted the war from Japan and rarely visited the Korean peninsula didn’t help. Roberts (presumably) quotes Lord Salisbury: ‘The study of large-scale maps drives men mad.’ Petraeus (presumably) concludes that a commander need not be on the front line, but a commanding general (i.e. the campaign commander) ‘does at least need to be in the same country as the theatre of operations’. Obvious? We didn’t get it right in the Falklands. In the end, say the authors, MacArthur simply couldn’t adjust to the idea of limited war. He was overburdened by experience.

The book’s trajectory is towards Ukraine, and with it the stark warning that war is not linear and in one direction. War can regress. It has in Ukraine, and the West is unready for any similarly prolonged state-on-state conflict. (Incidentally, at least one of the endorsers has in the past publicly questioned the likelihood of future state-on-state conflict.) Petraeus and Roberts do indeed enlighten and provoke thought – as well as disagreement; for as Clausewitz wrote, war is first an affair of ‘primordial violence… a blind, natural force’, and its art lies in the ‘play of chance and probability, within which the creative spirit is free to roam’.

Victory to Defeat is an equally thought-provoking book, if with a narrower, sharper focus: the parlous state into which the British army fell between the wars. Besides being meticulous history, it is in fact a polemic, a ‘cautionary tale for modern Britain’, say the authors. Richard Dannatt, as chief of the general staff (head of the army) in the Blair/Brown years, was notable for speaking his mind. ‘I want an army in five or ten years’ time,’ he said when he took over in 2006. Fourteen years after stepping down, the army is not the one he wanted, nor, he warns, what will be needed. Robert Lyman, a former soldier, is one of the surest, most astute and diligent of military historians writing today. Their analysis of why and how the British army of 1918 – magnificently triumphant in ‘the 100 days’ of mobile warfare that utterly broke the Germans on the Western Front – became the ill-equipped, ill-trained and ill-led expeditionary force chased out of France and Belgium in 1940 is indeed compelling.

Not only did the British army go to France in 1939 without the right equipment, it went without doctrine

The answer isn’t just political purblindness and stinginess. The fault initially lay with the army itself. The predominant feeling in 1919 was ‘back to business as usual’ – the empire, not the continent. No one therefore set about codifying what it was that had delivered victory, and for the Germans defeat. On the other hand, the Germans, with their enforced rump of an army, did precisely the opposite. It was not until 1932 that a formal study was made, but not much came of that either. For a dozen years the general staff had been trying to incorporate this and that lesson somewhat haphazardly into its written doctrine, but against a background of internal and external doctrinal zealotry – particularly regarding ‘mechanicalisation’ – had failed to impose a common understanding throughout the imperially spread army.

Consequently, it proved difficult to prioritise R&D and spending, particularly perilous at a time when the army was taking the scrapings of the barrel. Not only did the army go to France in 1939 without the right equipment (despite the best efforts of Leslie Hore-Belisha, one of the few political heroes of the book), it went without doctrine. It was saved to fight another day only by the remarkable ability of the British to conduct evacuations: Corunna, Gallipoli, Dunkirk (and Kabul in 2021).

The difference today is that while the army may not have the right equipment (and certainly not enough of it), or many men, it does at least have doctrine. And it could probably conduct a creditable evacuation too. But, as Churchill said in 1940, wars are not won by evacuations. Perhaps our leadership, having read the beginning of Conflict, might also read at least the epilogue of this sobering book.