During international or civil wars, private citizens of noncombatant nations often provide medical aid to one of the contending factions, particularly when they support a participant not favored by their own government. This paper details and analyzes the prominent campaign in the United States, Canada and Great Britain to provide medical aid to the Republicans during the Spanish Civil War (1936 to 1939). The substantial medical aid that was provided clearly alleviated some suffering, but one of the major objectives of the campaign was to arouse public opinion sufficiently to end the boycott of military aid to Republicans; this objective was never achieved. Whether it be in Republican Spain, Vietnam or El Salvador, even a successful medical aid campaign to people in a military conflict may save some lives but may not affect substantially the course of the conflict. Those who are primarily interested in influencing political or military developments, hoping to advance the cause of a particular contending faction, may find tactics other than medical aid campaigns more useful in accomplishing their goals.