George Samuel Montague Nathan (20 January 1895-16 July 1937) was half-Jewish (but referred to himself a Jewish later in life), born in London, and a volunteer in the International Brigades.
During World War I he fought on the Western Front as part of the Royal Warwickshire Regiment in the British Army. After spending time in India he went to Ireland as part of the Auxiliary Division of the Royal Irish Constabulary, where he was involved in the assassination of Sinn Féin members; George Clancy, Mayor of Limerick and Donal O'Callaghan, Mayor of Cork during the 1920s.
Nathan joined the International Brigades in 1937, as part of the so-called "British Battalion". This was attached to the XV International Brigade, which Nathan was made the Chief of Staff. Ironically, considering his ruthless murder of Sinn Féin mayors in the 1920s, this put him in control of the Marxist useful idiots of the Connolly Column under Frank Ryan. Nathan attempted to join the Communist Party, however, because he was a homosexual he was rejected, though Comintern admired him. He was killed the Battle of Brunete.