Jack Waters, better known as Samuel Wiederhorn, was a Jewish New Yorker, born on August 11, 1911, in eastern Bronx. He spent 4 years in the military as a mechanic for the 104th Artillery regiment from 1928 to 1931, enlisting after having received a high school diploma (no info found on attended schools). He became a member of the Young Communists' league during this time, as a unit organizer and later mechanic in 1933. Due to this, he had a military background previously to joining the fight in the Spanish Civil War. In 1935, he received a Spanish passport from the Soviet Union, and in 1937 flew from Moscow to Spain along with other members of the Lincoln Battalion.
Initially low grade, he became Adjutant Commander and later promoted to Commissar of his unit, while also being the unit's gun lieutenant. He was described by Sam Carsman in his memoir as someone who maintained good relations with members of his unit. A moment specifically described is when he led his unit on a drunken half-naked midnight drill in the snow, leaving many of the Spaniards there bewildered. From 1937 on, the John Brown Battery (which he was a part of) stayed on the Toledo Front, experiencing little action, until being sent back in 1939 along with the other international brigades.
Once the war in Spain was over, Wiederhorn's story was not finished yet. Now a hardened veteran, Wiederhorn joined the U.S. army as a 1st Lieutenant, although not much of his story is known during the war. Judging from the 1940 census, it seems that Wiederhorn may have been an Insurance Agent for the rest of his life, and kept close ties with other members of his family, such as Max Wiederhorn, another known communist.
Interestingly enough, both he and Max were put on a list of suspected communists in 1956, and as to whether or not they had continued to be communists up to this point, is entirely up for debate. In 1998, aged 86 years old, Samuel Wiederhorn died in the Upper West Side, and was buried in, surprisingly, a graveyard in Calverton, Suffolk County, far from his previously-known family or home.
https://albavolunteer.org/2015/07/blast-from-the-past-artillery-series/ - Concerning the John Brown Battery.
https://albavolunteer.org/2015/07/blast-from-the-past-memoir/ - Sam Carsman memoir which gives insight into Wiederhorn’s personality.
https://alba-valb.org/volunteers/jack-waters/ - A very useful source that goes over Wiederhorn’s life
https://www.ancestry.com/imageviewer/collections/2442/images/m-t0627-02490-00471?ssrc=&backlabel=Return&pId=2601844 - 1940 census