Conquest has always been an economic proposition. Armies cost money, and territory that cannot pay for its own garrison becomes a liability. For most of history, occupiers solved this problem crudely. They seized grain, livestock, and treasure, then moved on or settled in. The rise of industrial economies changed that calculation in ways that still shape how occupations unfold.

An industrial economy is not a granary to be emptied. Its value lies in coordinated production: factories, railways, banks, skilled labour, and the institutions that bind them together. That value cannot simply be carried away. It has to be managed, and management requires at least some cooperation from the people being occupied.

This creates a structural tension at the heart of every modern occupation. The occupier wants maximum extraction at minimum cost. The occupied population holds a quiet form of leverage: the ability to work slowly, withhold, or redirect. Between these poles sits a third group, those who find cooperation profitable. Understanding occupation means understanding how these three economic logics interact and shift over time.

Occupiers draw value from controlled territory through roughly three channels: direct seizure, fiscal extraction, and monetary manipulation. Direct seizure, meaning the requisitioning of food, metals, machinery, and rolling stock, is the oldest and most visible. It is also the least efficient over time. Requisitions disrupt production and encourage farmers and firms to hide output. They often yield less in the second year than in the first. Plunder consumes its own base.

Fiscal extraction is subtler. After 1940, Germany required France to pay 'occupation costs' of 20 million Reichsmarks per day, a sum far exceeding the actual expense of stationing troops. After November 1942 the payments rose to 25 million a day, and they absorbed a large share of French state revenue. The French administration collected the money through its own tax system. The burden therefore arrived in familiar bureaucratic form rather than at bayonet point.

Monetary manipulation completes the toolkit. Germany fixed the franc at 20 to the Reichsmark, well above the mark's market value, so German soldiers and firms could buy French goods cheaply. Through clearing accounts, occupied countries delivered goods to Germany in exchange for credits that were never meaningfully repaid. In effect, these were forced loans. Japan used a cruder version across Southeast Asia, issuing military scrip in such volume that it became nearly worthless and transferred wealth through inflation.

The comparative pattern is revealing. The most sustained extraction came from operating through existing institutions such as tax offices, central banks, and firms, rather than from plunder. Political scientist Peter Liberman argued that industrial societies can be exploited quite effectively because their administrative structures can be repurposed. The more sophisticated the economy, the more value can be extracted, but only if the occupier keeps the machinery running. Extraction, in other words, is less about taking than about redirecting flows.

Takeaway

Sustained extraction depends on keeping the occupied economy functioning. The most effective occupiers took through existing institutions rather than around them, turning local tax offices and central banks into instruments of transfer.

If extraction depends on functioning institutions, then resistance can target the functioning itself. Armed partisans attract the most attention in histories of occupation. Economic resistance, however, was often more widespread and, in aggregate, more consequential. It operated through countless small decisions: a worker who slowed the line, a farmer who underreported a harvest, a clerk who misfiled a requisition order.

The 1923 occupation of the Ruhr offers a striking case. France and Belgium seized Germany's industrial heartland to enforce reparations deliveries, and the German government responded by calling for passive resistance. Miners, railway workers, and officials refused to cooperate. Mines idled and trains stopped. Coal deliveries collapsed compared with pre-occupation levels, and France had to import its own engineers and railway staff at considerable expense. The occupiers discovered that controlling territory is not the same as controlling production.

Yet the Ruhr also reveals what resistance costs. Berlin financed the campaign by paying idle workers, largely by printing money. That accelerated the hyperinflation that wiped out German savings that year. Economic resistance is a contest of endurance, and the side that runs out of resources first concedes. By September 1923, Germany called off the campaign, having inflicted costs on the occupiers but absorbed greater ones itself.

Beyond refusal, occupied populations built alternative networks. Black markets diverted goods away from official channels where they could be requisitioned. Underground presses, clandestine relief funds, and informal credit arrangements created parallel economies beyond the occupier's reach. In occupied France, the compulsory labour scheme introduced in 1943 pushed many young men to evade conscription, and a substantial number joined the maquis. Extraction policies that squeezed too hard generated the very resistance they sought to prevent.

Takeaway

Resistance often works by raising the cost of extraction rather than ending occupation outright. It is a contest of endurance in which the side that exhausts its resources first gives way.

Every occupation depends on collaborators, and their motives are frequently more economic than ideological. Firms needed contracts and raw materials to survive. Officials needed salaries and wanted to keep their posts. Workers needed wages and ration cards. In a controlled economy, the occupier allocates scarce inputs, and access to those inputs flows disproportionately to those who cooperate. Refusal, by contrast, often meant idle plants and unemployed workforces.

Belgian business leaders in the Second World War developed an explicit framework for this dilemma. The so-called Galopin doctrine, named after Alexandre Galopin of the Société Générale, drew on the bitter memory of the First World War. It held that Belgian industry should keep producing for civilian needs to prevent famine, worker deportations, and the dismantling of factories, while avoiding direct armament production. In practice, the line proved difficult to hold, and Belgian output contributed substantially to the German war economy.

The underlying logic is one of hedging under uncertainty. Collaboration is a bet on the occupier's permanence. In 1940 and 1941, when German victory seemed plausible, cooperation appeared to promise high returns. After Stalingrad in early 1943, the calculation shifted. Firms and officials began quietly reinsuring. They maintained contacts with resistance movements or governments-in-exile while continuing to fulfil contracts. Collaboration rarely ended abruptly. It eroded as expectations changed.

Douglass North's emphasis on credible commitment illuminates this dynamic. Occupiers can offer contracts, but they cannot credibly promise to remain. Collaborators therefore face a time-inconsistency problem: today's rewards may become tomorrow's liabilities. Post-war purges, confiscations, and trials across liberated Europe confirmed that risk. At bottom, the economics of collaboration concerns how individuals price the future when the institutions governing it are contested.

Takeaway

Collaboration is less a fixed loyalty than a wager on which institutions will endure. When expectations about the future shift, so do the incentives to cooperate.

Modern occupation is a three-way economic negotiation. Occupiers seek to redirect flows of value. Occupied populations can raise the cost of that redirection. Collaborators trade cooperation for access, protection, and a stake in an uncertain future.

The structural lesson is that industrialisation transformed conquest. When wealth resided in granaries, it could be seized. When it resides in coordinated production and trusted institutions, it must be operated, and operation requires consent, however coerced or partial.

This dependence gives even defeated societies a measure of leverage. In any occupation, the question is not only who holds the guns. It is also who keeps the ledgers, runs the trains, and decides how hard to work tomorrow.