Andrew Roberts, one of the leading historians and biographers of our time, discusses his latest book Conflict: The Evolution of Warfare from 1945 to Ukraine, co-authored with General David Petraeus, along with insights from his biographies of Churchill and Napoleon.
The conversation spans why the second half of the 20th century avoided catastrophic great-power war, what determines who wins post-1945 conflicts, the failures in Iraq and Afghanistan, the war in Ukraine, the future of warfare, and the leadership styles of Churchill and Napoleon.
Nuclear weapons as the defining constraint on post-1945 conflict
Roberts argues the single biggest difference between the first and second half of the 20th century is the invention of the nuclear bomb.
Despite hundreds of wars since 1945 (roughly 140), all have been fought as limited wars because of the existential threat of nuclear escalation.
Pre-nuclear deterrence arguments existed before WWI (heavy artillery, industrial killing capacity), but those weapons could not obliterate entire cities in a moment the way nuclear weapons can, making the psychological and strategic barrier fundamentally different.
Strategic leadership as the decisive factor in war
Drawing on case studies from the Chinese Civil War through Iraq and Afghanistan, Roberts and Petraeus identify four key tenets of strategic leadership that best predict victory:
Getting the big idea for the war right
Communicating it effectively to lieutenants and the wider nation
Implementing it aggressively and efficiently
Continuously adapting the big idea as circumstances evolve
The Chinese Civil War illustrates this: the Nationalists under Chiang Kai-shek had more men, all the major cities, and superior weaponry, yet lost because of poor strategic leadership, including warlords who refused to carry out plans.
By contrast, Zelensky in Ukraine exemplifies all four qualities: a clear big idea (“I need ammunition, not a ride”), effective communication, aggressive implementation, and adaptation.
Failures in Iraq and Afghanistan
The US invasion of Iraq suffered from a critical planning gap: the generals who planned the invasion to topple Saddam were different from those responsible for post-regime security and stability.
The decision to dissolve the Ba’ath Party and disband the army without a plan for how those men would feed their families while allowing them to keep their weapons created a recipe for insurgency.
The soldiers who executed the invasion itself performed excellently; the failure was in strategic leadership at the top regarding what came after.
Iraq and Afghanistan lacked leaders with the qualities of a Zelensky.
Roberts attributes this partly to the sectarian and tribal nature of those societies, which makes national unity under one leader far harder than in Ukraine.
Maliki, Karzai, and Ghani (who fled with suitcases full of money) all lacked the ability to command broad loyalty across sectarian lines.
Ukraine and the limits of Western support
Zelensky’s goal is clear: Ukraine will not accept 18–19% of its territory remaining under Russian control and will fight to reclaim it.
When Roberts and Petraeus visited Kyiv, they found unanimous national unity on this goal among generals, ministers, and ordinary citizens alike.
The American goal is less clearly articulated and has been executed piecemeal: waiting for allies to provide advanced weapons first, then following suit, escalating only when the Russians do not retaliate.
This approach delayed critical capabilities like Leopard tanks and long-range artillery that Ukraine needed for its southern counteroffensive.
Roberts argues the US lacks the political will to arm Ukraine wholeheartedly all at once, but Ukrainians will continue fighting regardless because they will not accept America dictating their national destiny.
The war has become a bloody slog reminiscent of the Korean War, with Russia having built miles of minefields in the south.
The Korean War and the nuclear taboo
Roberts gives Truman significant credit for preventing nuclear war by rejecting MacArthur’s proposal to use nuclear weapons against Chinese forces crossing the Yalu River.
Had MacArthur used them, he might have won the Korean War, but the moral barrier against nuclear use would have been dramatically lowered, making nuclear weapons a regular feature of warfare in the 1950s and beyond.
British Prime Minister Clement Atlee also deserves credit for flying to Washington to express concern about MacArthur’s nuclear talk.
Truman’s decision to sack MacArthur was itself significant: MacArthur was enormously popular and politically ambitious, and some contemporaries believed he could have led a march on the Capitol had he chosen to.
Deterrence and Taiwan
Roberts argues deterrence is not dead; it works well against rational actors.
Xi Jinping wakes up each morning and weighs the costs of invading Taiwan against American military power in the South China Seas and the hostility of nearly all his neighbors, and decides today is not the day.
American strategic ambiguity, combined with the sheer scale of the US military budget, makes the risk unacceptable for a rational Chinese leader.
Deterrence fails only against irrational actors who do not fear annihilation, such as Hamas, whose ideology frames violence as a religious duty regardless of consequences.
Taiwan’s strategic importance goes beyond its 23 million people: it produces roughly 80% of the world’s high-end semiconductors, making its seizure by China catastrophic for the global economy.
Even in a blockade scenario, where China puts the onus on America to initiate kinetic war, the Pentagon has war-gamed these situations extensively, and Xi must account for the possibility that an American president would go all in, especially given the coalition leadership the US has demonstrated in Ukraine.
Churchill as applied historian
Churchill was a professional historian in the 1930s, writing multi-volume works including a biography of his ancestor the Duke of Marlborough, which functioned almost as a rehearsal for his own leadership in WWII.
History provided him with constant signposts on tactics, strategy, alliance management, and domestic political communication.
Roughly 10% of his WWII speeches contained historical references, drawing analogies to the Spanish Armada and the Napoleonic Wars to tell the British people they had faced existential peril before and prevailed.
Roberts rejects the characterization of Churchill as merely emotional or principled rather than rational.
Churchill’s opposition to appeasement at Munich was a hard-nosed assessment of the balance of power: Germany’s military buildup in the year between the Sudeten crisis and the outbreak of war, combined with its capture of the Skoda arms factories, made stopping Germany earlier the strategically rational choice.
Churchill was also deeply forward-looking in technology.
He had close relationships with scientists like Professor Lindemann (later Lord Cherwell), whom he described as being “on tap but not on top.”
As early as the mid-1920s, he wrote about the possibility of a nuclear bomb the size of an orange destroying an entire city, roughly 20 years before the atom bomb.
He was fascinated by radar, codebreaking (Ultra), and wanted to understand the technical details of these capabilities.
Why democracies win wars but lose elections
A recurring pattern in democratic countries is that victorious wartime leaders are voted out of office after the war ends: Churchill in 1945, Lloyd George after WWI, De Gaulle resigning in 1946, George H.W. Bush after the Gulf War and the peaceful end of the Cold War.
Roberts argues this is rational: the skills required for wartime leadership are fundamentally different from those needed in peacetime.
In 1945, the British public wanted the welfare state, nationalization, and a New Jerusalem, which Labour under Attlee promised more credibly than Churchill’s Conservatives, even though Churchill would have implemented many of the same policies.
The shifting balance between offense and defense
Roberts and Petraeus observe that the balance of power has shifted toward defense in recent decades.
Clausewitz’s classic ratio held that attackers needed a 3:1 advantage over defenders, and this remained roughly true through WWII.
In urban warfare with IEDs, booby traps, tunnel networks, snipers, and ambush tactics, the required ratio has increased significantly beyond 3:1.
Historical examples support this: at Monte Cassino, rubble from destroyed buildings actually gave defenders better positions for machine gun nests; in Stalingrad, the close-quarters “rats’ war” in sewers and buildings produced devastating casualties for attackers.
Roberts warns that the IDF’s potential ground operation in Gaza could resemble Stalingrad in its brutality and cost.
Could Hitler have won WWII?
Roberts argues in The Storm of War that Hitler’s ideologically driven blunders were the primary reason Germany lost, and that without them, victory was conceivable.
The single greatest blunder was declaring war on the United States after Pearl Harbor, driven by Nazi racial ideology that held Jews and blacks dominated American decision-making and that Americans were cowards incapable of fighting.
Hitler told Molotov in 1940 that American troops could not reach the European theater until 1970; in reality, a quarter of a million GIs landed in North Africa by November 1942.
The invasion of the Soviet Union was similarly ideologically motivated: the belief that Slavic peoples could not resist the Aryan master race and that the Bolshevik state would collapse immediately.
Even without a declaration of war on the US, Lend-Lease aid to the Soviets would have continued, and the Eastern Front was where four out of every five German battlefield deaths occurred.
American industrial output was staggering: in 1944, the US produced 98,000 warplanes compared to 28,000 for Britain and 40,000 each for Germany and the Soviet Union; Liberty ships were built at a rate of one per week.
Roberts contrasts Hitler’s leadership style with Stalin’s.
After his initial breakdown upon learning of Operation Barbarossa, Stalin adopted a more Western, collegiate approach, empowering marshals like Zhukov and Rokossovsky and genuinely listening to their advice.
Hitler, by contrast, held hours-long meetings at the Wolf’s Lair where his generals presented detailed strategic analysis, only to have Hitler sum up by insisting on his original plan regardless of what had been discussed. Stenographic records of these meetings survive and make this dynamic clear.
Surprise attacks and whether they can still happen
Dictatorships and authoritarian regimes are better at starting wars because they can achieve surprise; democracies generally cannot or do not.
Historical surprise attacks include Pearl Harbor, Barbarossa, the Yom Kippur War, 9/11, the Falklands invasion, Saddam’s invasion of Kuwait, and China’s entry into the Korean War with 160,000 troops crossing the Yalu River undetected at night.
Paul Wolfowitz’s observation: surprise attacks happen so often that the only surprising thing is that we remain surprised by them.
The one major exception is Israel’s successful surprise attack in the Six-Day War.
Surprise attacks tend to backfire by lighting a fire in the attacked nation: Pearl Harbor unified American public opinion for total war, and Hamas’s October 7th attack, while tactically successful, has provoked an overwhelming Israeli response.
Roberts is skeptical that large-scale nation-on-nation surprise attacks remain possible given satellite reconnaissance, drones, and cyber espionage.
However, the Hamas attack shows that smaller-scale surprises are still achievable, and the psychological impact of being surprised remains powerful regardless of technology.
The future of warfare
Roberts and Petraeus argue that future wars will be fought primarily between drones and autonomous systems, with humans “on the loop” (having written the algorithms) rather than “in the loop” (making real-time decisions).
Decision-making will need to happen far faster than the human mind can process, meaning any human-controlled system will lose to an automated one.
Machines have no conscience, fear, cowardice, remorse, or pity, making future warfare potentially more dangerous and less constrained.
The electromagnetic spectrum will become a critical contested domain, as jamming communications between autonomous devices becomes a key tactic.
Tech entrepreneurs are now playing a role in warfare comparable to industrialists like Krupp and Thyssen before WWI.
Elon Musk’s Starlink has been invaluable to Ukraine, enabling real-time battlefield intelligence through iPhones that feed targeting data to drones and artillery, which was a key reason Kyiv did not fall in the early stages of the war.
Musk notably refused to activate Starlink for a planned Ukrainian naval surprise attack on Crimea, showing that individual tech leaders can now make strategic decisions that affect the course of wars.
Roberts sees this as broadly positive for the West, since the cutting edge of technology and entrepreneurial ability remains concentrated in Western democracies.
Napoleon as startup founder
Roberts was surprised to learn that a “cult of Napoleon” exists in the startup community, where his biography is considered part of the canon.
He sees the parallels clearly: Napoleon was a young, energetic upstart who outcompeted established bureaucracies, was intellectually curious and self-taught, and was obsessed with innovation in agriculture, chemistry, bridge-building, and military technology.
He created prizes for scientific breakthroughs, attended meetings of the French Academy as First Consul, and actively recruited intellectuals, scientists, and inventors to help France outstrip Britain in the Industrial Revolution.
He was also a meritocrat: 13 of his 26 marshals came from the working class or below, including sons of innkeepers and barrel coopers, and some became kings.
Roberts notes the megalomania risk is real: hubris is the occupational hazard of hugely successful people, and Napoleon’s invasion of Russia in 1812 was the turning point after which nothing good happened.
However, Roberts pushes back on the idea that the 1812 invasion was pure insanity: Napoleon had beaten the Russians twice before, commanded an army of 615,000 (the size of Paris at the time), and expected a short campaign. The catastrophic retreat was driven by factors beyond just the weather, including the continental blockade strategy against Britain that was the truly hubristic policy.
Roberts speculates that a Napoleon born today would go to Silicon Valley, found a company, acquire competitors, and become a billionaire.
The power of biography as a historical medium
Roberts has written 20 books, many of them landmark biographies, and argues biography is the best medium for understanding an era.
It focuses the mind on a single individual, creates emotional connection, and illuminates how individual decisions shape world-changing events.
He rejects the deterministic view (held by Marxists and Whig historians) that biography is antithetical to understanding large historical forces: decisions like Churchill’s refusal to make peace with Hitler in 1940 or Napoleon’s invasion of Russia in 1812 were individual choices with enormous consequences.
Both Churchill and Napoleon wrote autobiographical novels in their early twenties in which the hero saves the country and wins a fair maiden; Roberts confesses he did the same thing in his twenties.
Roberts’s productivity
Roberts writes his books while serving in the House of Lords (attending Monday through Wednesday) through extreme time management.
He starts work at 4:00 AM every day, getting roughly five hours of uninterrupted work before anyone contacts him.
He takes a 30-minute nap every afternoon, a habit he began at Cambridge 40 years ago, which he says effectively gives him two days of work for every one day on Earth.
