Nationalist Spain lacked the sort of institutionalized units of foreign volunteers that the Republic had, with most foreigners being either part of national contingents sent as aid (German, Italian), or de facto equivalents (Portugal). The Spanish Foreign Legion was mostly just Spaniards, and what national volunteer units, such as O'Duffy's Irishmen, were fairly small. There was no 'American' Unit comparable to the Abe Lincolns, but there were a small number of 'one off' volunteers, either out of ideology or simply soldiers of fortune, who fought on Franco's side.

One such example would be Vincenzo Patriarca, a New York pilot and son of Italian immigrants, who had left for the motherland in 1934, and after a brief stint flying tour planes in Trieste, joined the Airforce and flew over Ethiopia. He was kicked out of the service for medical issues, but in 1936 Nationalist agents recruited him and he was soon flying a fighter plane escort as the Army of Africa was air-bridged to Europe. His career was shortlived. He suffered a mid-air collision with a Republican plan in September, survived the crash, but was captured. The US Embassy was successful in getting his release, eventually, and he was back in the USA by 1937, only to return to Italy and get himself readmitted to the Airforce there, again to be kicked out when America joined the war putting his loyalty into question, although he was eventually let back in and he continued to serve in the Italian air force through the 1950s, serving as a NATO test pilot.

Patriarca wasn't alone, but quite close, as he was one of roughly ten or so Americans - almost certainly one of the lowest numbers relative to population size at least - who joined the Nationalists in Spain, but we don't know much about many of them beyond their names! Albin Arnold and Guy Stuart Castle served in the Foreign Legion, both being wounded, and the latter attempting to desert while recovering, only to be caught and sentenced to death. Castle's sentence was commuted though, and he was turned over to American diplomats to return home, where he would eventually join the Rangers during WWII.

They are joined by a few other names, including Manuel Martin and Francisco Noriega, but the Foreign Legion, unlike the French counterpart, was mostly Spanish, and they would have served as part of the unit, not as part of an American contingent. A journalist named Thomas P. Krock claimed to have served as a general for a time, but there seems to have been no records supporting this, and it is questionable if he was in the military there at all. Joseph Eastman Sheehan, a plastic surgeon, operated in Nationalist territory and although not a soldier proper, was given an honorary colonelcy.

Franco's International Brigades by Christopher Othen