How Modern Wars Are Really Won: Lessons from O'Brien's War and Power

Modern wars aren't won on battlefields - they're won in factories, ports, and alliances. Insights from Phillips Payson O'Brien's War and Power on systemic warfare.

We like to think wars are won on battlefields. The decisive charge, the brilliant maneuver, the general who outsmarts his opponent - that is the picture most of us carry around. Phillips Payson O’Brien’s War and Power argues we have been looking at the wrong layer the whole time.

His central claim is simple enough, and I think it holds up. Great-power wars are not decided by tactical brilliance, or even by operational superiority. They are won by whoever can better keep running the systems that make war possible at all - industry, finance, logistics, energy, shipping, and the networks that tie all of it together.

World War II: the battles were the symptom

The conventional story of that war is a sequence of turning points. Stalingrad, Midway, D-Day. O’Brien reads those as symptoms of Allied victory rather than causes of it.

It helps to look at what the two sides were actually doing. Germany and Japan fought wars aimed at destroying enemy armies and taking territory, and they were very good at it. The Wehrmacht’s early campaigns were masterpieces of operational art, and Japan’s conquests across the Pacific were breathtaking in both speed and scope. They won spectacular battles for years.

Then they lost the war.

The Allies were playing a different game. Instead of concentrating on destroying Axis armies, they went after the ability of the Axis to function as modern states at war at all - sinking merchant shipping, bombing industrial production, cutting off access to oil and capital markets, isolating them economically. The decisive advantage was never that American soldiers were better trained than German ones. It was that America could build ships faster than Germany could sink them, aircraft faster than they could be shot down, and tanks faster than they could be destroyed. And it managed all of that while holding together a coalition that gave it British intelligence, Soviet manpower, and bases and supply lines spread across the world.

Victory didn’t follow from brilliance on the battlefield. It followed from systemic dominance.

Coalitions stopped being optional

O’Brien makes two extensions to this, and the first is that great-power war is now coalition warfare by default.

Modern war is too complex, too expensive and too dependent on systems for any single power to fight alone. The Allied advantage wasn’t American industrial capacity sitting there on its own. It was a working alliance that integrated industrial capacity, financial systems, shipping and logistics, and - harder to measure, but just as real - a shared sense of purpose.

The Axis never had that. Germany, Japan and Italy didn’t share systems. They coordinated armies. There was minimal industrial integration, limited technology transfer and effectively no shared financial infrastructure. Those were transactional partnerships, held together by immediate military necessity, and nothing much deeper. The Allied coalition, for all its friction, worked as a single organism.

The lesson for the present is fairly blunt. The wars that come will be won by whoever can build and keep alliances of states that actually choose to be there, share the burden, and integrate their systems over time. Coerced partners and ad-hoc alignments look fine on paper. They come apart under prolonged stress.

This changes what the competition is even about. The question stops being who has the better weapons and becomes who can align more of the world’s productive and connective capacity on their side. Ports, semiconductor fabs, undersea cables, shipyards and financial plumbing sitting inside allied states are not civilian bystanders in that contest - they are war-making capacity. Where those capabilities sit in the world arguably matters as much as how many tanks or missiles anyone can count.

War is a whole-of-society problem

The second extension restores something the industrial age made obvious and we’ve since managed to forget. War is not primarily a military affair. It is a societal one.

Fighting a great-power war asks a society to keep industrial mobilization going for years, accept economic sacrifice, hold together under stress, and tolerate a good deal of disruption and loss. A population unwilling to carry those costs cannot hold up the systems that war actually runs on, and it doesn’t matter how advanced the weapons are. The center of gravity is public belief that the war is necessary and legitimate, as much as it is any factory or naval base.

The Second World War shows this clearly enough. Allied societies accepted rationing, mass conscription, the bombing of their own cities and years of economic hardship, and the consent behind all of it was real and lasting. Axis societies were brittle by comparison. Propaganda stood in for consent, military success covered for an increasingly fragile social contract, and when the military tide turned those societies cracked.

What this means now

Wars among great powers in this century will be long, economically disruptive and invasive in a way that doesn’t stay at arm’s length. None of that will be confined to distant battlefields. It shows up in energy prices, in what you can buy, in employment, in what information reaches you. And it will keep asking for sacrifice.

Victory, on this reading, belongs to societies that can explain plainly why the struggle matters and that treat resilience as a civic habit rather than a temporary wartime measure. That is what makes public consent last for years instead of months, and it is what lets economic policy line up with the strategic objective instead of quietly working against it.

O’Brien goes further, and this is the part worth sitting with. A modern great-power war may already be underway - in semiconductors, shipping routes, financial systems and energy infrastructure. Export controls on advanced chips, financial sanctions, supply-chain realignment, industrial policy aimed at bringing critical production back home. These are not the run-up to a conflict. They are the conflict. Kinetic war, if it comes, would mostly accelerate what is already moving.

The shift

So the shift O’Brien asks for is a large one. Stop thinking mainly about winning battles and start thinking about owning the conditions that keep a war winnable.

In practice that means:

• Building alliances on deep systemic integration, rather than military coordination alone
• Investing in supply chains for critical goods that survive disruption
• Keeping industrial capacity even where it is economically inefficient in peacetime
• Cultivating societal resilience, and some public understanding of what great-power competition actually involves
• Treating ports, cables, fabs and financial infrastructure as strategic assets and not purely economic ones

Once war is systemic, the line between economic and military power stops meaning much. The capacity to produce, to move things, to pay for them and to coordinate complex operations at scale is military power.

Which reframes the question any great power should be asking itself. Not “can we win the next war?” but “can we build and hold the alliances, the industrial base and the social cohesion to prevail in a contest that might run for years, or decades?”

O’Brien’s answer is that the traditional metrics - divisions, aircraft, ships - are necessary and nowhere near sufficient. The real measure is whether you can keep your society producing, your allies committed and your systems working when everything is under maximum stress.

That is a very different kind of preparedness than the one we are used to. And it may be the only kind that counts.