Zalmans Jakubs was born in 1919 in Dvinsk (Dünaburg; present-day Daugavpils, Latvia's second largest city). He graduated from Hebrew school (beginning with Torah be-Derekh Eretz and ending at the 2nd Jewish General School). He then worked at a toy workshop.
With the beginning of the Soviet-German war in June 1941, the Jakubs family was able to escape into Soviet Central Asia. There, in January 1942, Zalmans was drafted into the Red Army and sent to the Gorokhovetskii camp, Russia, where the 201st (later 43rd Guards) Latvian Division was being formed. In the camp, Zalmans was trained as a mortar gunner. In October 1942, when the division was deployed to the Northwestern Front, Russia, Sergeant Jakubs became the commander of a mortar unit made up of soldiers who spoke only Yiddish. On December 31, 1942, while taking part in a Red Army offensive east of Pskov (western Russia), Zalmans was wounded for the first time. After being treated, he returned to the front lines. In September 1944, while fighting in Latvia, Zalmans was seriously wounded. After being discharged from the hospital, he was sent to Germany to work as a translator at the Soviet commandant's office in Nauen, 30 kilometers west of Berlin. It was there that he met V-E Day.
After the war, Zalmans Jakubs returned to Daugavpils. Most of his family had perished at the Daugavpils ghetto. He became an amateur historian of his city, specializing in its Jewish community – in fact, his first essays on the history of Daugavpils had been published before the war. Officially, Jakubs worked as a scrap and waste paper receiver at a collection point for recycling. It was said that Jakubs had chosen this job, which paid a beggar's salary, so as not to miss any historical documents or publications concerning the history of his city and the Jews of Latvia. He managed to publish his first (Yiddish-language) essay on Latvian Jewry only in 1987, during the period of Perestroika and official openness in the Soviet Union. Throughout his life, Jakubs authored about 600 articles, essays, and books in Yiddish, Hebrew, Latvian, and Russian, including monographs and collections titled Daugavpils in the Past, From the History of the Daugavpils Ghetto, Jews in Dünaburg – Dvinsk – Daugavpils, etc. In 2005, he was awarded the title of Honorary Citizen of Daugavpils.
Zalmans Jakubs died in 2009.