a resistance movement activist, member and co-founder of the Jewish Combat Organization (ŻOB) and the Antifascist Bloc, associate of Oneg Shabbat, manager of Ha-Shomer ha-Tsair
He was born in Kalisz. In 1926, he joined Hashomer Hatzair, a Zionist youth organization of a scout character. In a short time he became an instructor of the Kalisz divison, then he was elected to the district management. Together with Cwi Brandes, he founded a kibbutz in Żarki. He served in the Polish Army, after which he became a member of the management of Hashomer Hatzair.
At the outbreak of World War II Kapłan was in Warsaw, from where he headed east. In September and October 1939, he managed the action of transferring members of Hashomer Hatzair to Vilnius. He returned to the capital in February 1940 on the orders of the management. In the ghetto, he was involved in editing the underground press and organizing cooperation between the divisions of Hashomer Hatzair; he traveled to various places in order to strengthen the organization’s structures. During these trips, he kept a diary describing the life of Jews under German occupation in various Polish cities. Unfortunately, his work was lost during the Great Action in the Warsaw Ghetto.
In 1942, together with Szmuel Bresław, they were invited to the Oneg Szabat group, with which Kapłan collaborated until the very end. In March of the same year, he co-founded the Anti-Fascist Bloc. On July 28, he was among the people who founded the Jewish Combat Organization (ŻOB). Together with Tosia Altman, he organized youth groups. During the so-called Great Action, he worked at Gęsia 30 St. in the OSW shed (Ostdeutsche Bautichlerei Werkstette, also known as the “carpentry shed”), where he stamped false employment cards to his comrades, thus helping them avoid deportation.
Unfortunately, he did not live to see the outbreak of the Warsaw Ghetto Uprising, of which he was one of the initiators. On September 3, 1942, he was arrested by the Gestapo, imprisoned in Pawiak and sentenced to death, which was carried out on September 11 at the gate of the tenement house at Dzika St.