Source Columba

It involved air-dropping homing pigeons behind enemy lines in German-occupied France and the Netherlands as a means for locals to convey information, such as troop movements, to British intelligence.

In 1944, prior to the imminent Allied invasion, German counterintelligence sought to counteract (or co-opt) Source Columba by dropping pigeons of their own.

These pigeon cases, accompanied by a packet of English cigarettes, were purporting to be British also and carried instructions to communicate the names of the local patriots to the Allies.

Despite such interference, the operation was reported to have been remarkably successful, yielding useful intelligence in over fifty percent of the received messages.

31 Source Columba pigeons eventually received the Dickin Medal, the highest British military decoration for animals.