In 1944, following the Allied landings at Normandy, French resistance partisans began operating openly and on a large scale against German forces. Organized into the French Forces of the Interior (FFI), they were in contact with the Allied command and the Gaullist Provisional Government of France, although they operated under command independent from those forces. By wearing insignia visible at a distance, carrying their arms openly, operating under responsible command, and adhering to the laws of armed conflict, the FFI qualified as combatants as defined by the 1929 Geneva Convention.

The Germans, however, did not recognize the FFI as legal combatants. They took the view that, following the 1940 armistice, France was no longer at war with Germany, and so its citizens in the FFI were criminals, not combatants. The FFI for its part claimed that the Franco-German armistice had been breached and hostilities had resumed. By their reasoning, French forces fighting according to the 1929 rules had to be granted combatant rights, including prisoner of war status for captured fighters. Because Germany did not view the FFI as legal combatants, it killed numbers of them out of hand, by summary execution. On the day after the Normandy landings, for example, the Germans shot fifteen partisans captured at Caen.

As the scale of fighting in France increased, the German claim that the armistice and its terms were still legally in place became unsustainable. Nevertheless, the German forces continued to execute FFI fighters, even though Charles de Gaulle’s Provisional Government protested on behalf of the FFI and threatened reprisals. By late summer 1944, many German soldiers had surrendered to the FFI, and the FFI was in a position to act. When it became known to the FFI that the Germans had executed eighty partisans and planned to execute more, the FFI announced that it would carry out eighty reprisal executions. The International Committee of the Red Cross (ICRC) sought to intervene and obtained a postponement pending an agreement by the Germans to grant the FFI legal combatant status. After six days without a German response, the FFI executed eighty German prisoners. It appears that no further FFI fighters were executed after that.

Reprisal is a legal term in international humanitarian law (IHL) describing a particular kind of retaliation. To be a reprisal, it must be undertaken for the purpose of forcing, or inducing, enemy forces to cease their own violation of IHL. It is a self-enforcement of the laws of war, for reprisal is undertaken not in retaliation or punishment, but rather to force the other side to stop its violation. For this reason, a reprisal is technically an action that, if done on its own, would constitute a violation of IHL. When, however, it is done for the purpose of forcing an adverse party to cease violating IHL, it may become a legal act, providing all the legal criteria are met. Moreover, an act of reprisal, to be a reprisal and not mere retaliation, must be proportionate to the violation of IHL committed by the other side.

Today, reprisal has almost entirely disappeared from the canon of IHL. Even assuming that the German position on the legality of FFI combatants was wrong, the 1929 Geneva Convention specifically outlawed precisely this kind of reprisal using prisoners of war. Each successive revision of IHL treaties has put additional categories of combatants and civilians beyond the reach of reprisal actions. The 1949 Geneva Conventions extend the prohibition from prisoners of war to those civilians protected by the Fourth GenevaConvention, and Additional Protocol I of 1977 specifically extends the protection to civilians of any kind as well as to "civilian objects.” Perhaps the only circumstance in which IHL today still permits reprisal actions, if at all, is as a response to the use of illegal methods or weapons against combatants. The trend, clearly, is to outlaw reprisal under all circumstances.

The FFI killings of the German soldiers, although effective in stopping the German summary executions, were plainly a violation of IHL as then in force, and would certainly be a violation of IHL and a grave breach of the Geneva Conventions and Additional Protocol I today.

(See protected persons.)