Marcel Rosenberg (1896 — 5 March 1938) was a Jewish Soviet diplomat. the first Soviet ambassador to Spain, notably during Spanish Civil War. Recalled to the Soviet Union in 1937, he was soon executed during the Great Purge. He was succeeded in office by Leon Gaikis, who faced a similar fate.
"More than an ambassador, [Rosenberg] acted like a Russian viceroy in Spain. He paid daily visits to Largo Caballero, sometimes accompanied by Russians of high rank, military or civilian. During the visits, which lasted hours on end, Rosenberg tried to give the head of the Spanish government instructions as to what he should do in order to direct the war successfully. His suggestions, which were practically orders, related mainly to army officers. Such and such generals and colonels should be dismissed and others appointed in their place. These recommendations were based, not on the competence of the officers, but on their political affiliations and on the degree of their amenability to the Communists."
- Stalin and the Spanish Civil War: 2. Soviet Diplomacy and the Spanish Civil War http://www.gutenberg-e.org/kod01/frames/fkod04.html