Dawid Moryc Apfelbaum (some sources give Mieczysław or Mordechaj as his second name, and Appelbaum as his surname), nom de guerre "Kowal" ("Blacksmith") (?-4/28/1943) was allegedly an officer in the Polish Army and a commander of the Jewish Military Union (Żydowski Związek Wojskowy, ŻZW), during the Warsaw Ghetto Uprising (See Dawid Wdowiński.) In 1939 Apfelbaum was a Lieutenant in the Polish Army. During the German invasion of Poland he fought in the defence of the Polish capital Warsaw.
Moshe Arens, the author of numerous works on the Revisionist underground in the Warsaw Ghetto Uprising maintains that the "ZZW was led by Pawel Frenkel, a member of the Revisionist Youth Movement, Betar; Leon Rodal, a member of the Revisionist movement, and David Apfelbaum, a former officer in the Polish Army who was an adherent of Zeev Jabotinsky."
After Poland's defeat together with many other Jews in Polish Army as well as Polish-Jewish political leaders he founded the ŻZW. In structures of the organization, Apfelbaum purportedly was the chief of the department of communication with Korpus Bezpieczeństwa and Armia Krajowa on "Aryan" site of Warsaw. Together with Paweł Frenkiel he was also said to be a leader of the war department in ŻZW. In the meantime, Armia Krajowa secured his promotion to Captain from the Polish government in exile.