The Spanish State under General Franco was officially non-belligerent during World War II. This status was not recognized by international law but in theory amounted to neutrality. Franco's regime supplied material and military support to the Axis Powers in recognition of the heavy assistance it had received in the Spanish Civil War. Despite ideological sympathy, Franco did not bring Spain into the war as a belligerent and stationed field armies in the Pyrenees to dissuade a German occupation of the Iberian Peninsula. The Spanish policy frustrated German proposals that would have encouraged Franco to take British-controlled Gibraltar.[1]
Apparently volunteers fought for both sides.