Live-and-let-live system

The Live-and-let-live system was a set of unofficial, unspoken nonaggression conventions that took shape along the First World War front lines from 1914 and endured for at least two years. It did not end the war or reconcile the armies’ purposes. Instead, it allowed soldiers facing one another in fixed trench positions to limit hostile actions through reciprocal restraint, retaliation, and forgiveness. The book uses this local accommodation to show how cooperation can arise among self-interested participants when they expect to meet again and the future remains uncertain.

Origins and Conditions

The system was more than the brief fraternization between British and German soldiers commonly associated with Christmas. Across the front, opposing groups could remain in place for many months, and ordinary soldiers did not know when they would be transferred. That prolonged, indeterminate relationship gave each side reason to consider the consequences of its conduct toward the same opponents over time.

The circumstances resemble a repeated Prisoner’s Dilemma, but only at the level of the individual soldiers and the units directly confronting one another. The generals wanted their troops to attack whenever possible; the men at the front had an immediate interest in avoiding unnecessary danger. Although soldiers might prefer victory to defeat, the action of one individual was unlikely to determine the war’s outcome, whereas restraint or aggression by the opposing group could affect his own prospects. Mutual restraint could therefore be preferable to mutual aggression for the soldiers, even while it frustrated the military command’s aims.

How the Conventions Worked

The arrangement was not one centrally established policy. It developed through local responses to conduct: soldiers learned what their counterparts were doing and adjusted their own behavior. In one area, the stable pattern was not simply a direct, one-for-one response. A contemporary account described a rule of three retaliatory rifle grenades for every one received, illustrating how local conventions could differ while still making defection costly.

Retaliatory capacity remained visible, but it did not have to be used against people. Skilled marksmen on both sides demonstrated their ability by shooting at inanimate targets close to enemy soldiers. The display communicated that retaliation was possible without turning every demonstration into an attack. In this way, restraint did not mean the absence of threat; the credibility of a response helped protect the convention, while limits on its use prevented every exchange from escalating.

Forgiveness was equally important. A retaliatory rule that never allowed a return to cooperation could generate long, damaging cycles of mutual reprisal. The system instead included room for a hostile incident to be followed by an acknowledgment and a renewed accommodation. Its persistence depended on both sides being able to punish departures from restraint and to resume restraint after them.

Strategy Without a Plan

The conventions were not negotiated around a table or necessarily recognized by the soldiers as a developing system. They emerged from repeated local interaction, with participants responding to one another’s actions rather than designing a comprehensive agreement. The book compares this process to computer strategies whose behavior can be classified as cooperative, retaliatory, forgiving, or otherwise without the programs themselves being conscious of a strategy.

That comparison shifts attention from intention to conduct. A strategy counts as cooperative or forgiving because of what it does, not because its author or participant possesses a particular motive. The soldiers’ local accommodations thus illustrate how organized strategic patterns can arise without a formal plan or an explicit understanding among those enacting them. Their behavior, rather than a written rule, carried the arrangement forward.

Repetition and the Future

The system’s deeper significance lies in the uncertain duration of the soldiers’ encounters. In a one-off Prisoner’s Dilemma, the incentive to defect differs from the incentive in a repeated game. If both players know exactly when their interaction will end, the final round can become a one-off contest, and reasoning backward can make defection appear rational in every preceding round. In continuing real-life relationships, however, participants estimate how much longer interaction is likely to last, and those estimates can change as circumstances change.

A longer expected future makes cooperation, forgiveness, and reduced envy more plausible; an apparently short future makes immediate defection more tempting. At the front, soldiers could expect to keep facing the same opposing group, yet did not know when orders would move them elsewhere. That combination—a substantial but unpredictable future—helped support Tit for Tat-like cooperation. The Live-and-let-live system therefore exemplifies how repeated encounters can make reciprocal restraint viable without requiring the participants to abandon their opposing interests or consciously formulate a shared policy.