Vulya (Volf) Kotz was born in 1923 in Tver, in a Jewish family. His father was a photographer, while his mother was a hatter. He finished school in his native city. In 1940, Kotz moved to Leningrad and began to attend the Dzerzhinsky Naval Engineering High School (now the Naval Polytechnic Institute).
In late June 1941, Nazi Germany invaded the Soviet Union. By that time, Vulya had finished his first year of study. After completing an accelerated officer training course, Kotz was assigned to the 85th Naval Rifle Brigade. That brigade was formed in 1941 and dispatched to the north of the country, to oversee the delivery of aid from the Western Allies to the ports of Archangelsk and Murmansk. The brigade was made up mostly of 18-year-olds, all of them former classmates, who had been given the naval rank of starshina (petty officer). 10 out of the 37 graduates of Kotz's class were Jews.
Vulya Kotz's first posting was as a squad leader in a missile battery, and he was later transferred to a rifle battalion, where he became deputy commander of a rifle platoon. That unit took part in both defensive and offensive operations, and carried out intelligence-gathering missions on the Karelian Front. While there, Kotz endured manifestations of antisemitism on the part of the platoon commander.
In September 1942, Vulya Kotz took part in the poorly planned Ondozero Operation. A detachment of paratroopers was sent to liberate a Finnish POW camp in the village of Ondozero (Ontajärvi, now in the Republic of Karelia), but most of them were killed. The company in which Vulya Kotz served was supposed to rendezvous with the paratroopers in a neutral zone. After witnessing the deaths of the paratroopers on the lake, they tried to attack, but were forced to retreat amid heavy losses.
Vulya Kotz ended the war in the rank of junior sergeant, commanding a mortar platoon. He had served in the Northern Fleet throughout the war. He was awarded the Order of the Red Star and several medals.
After the end of the war, he returned to Leningrad and resumed his studies, graduating in 1950. He later worked in designing and testing submarines at a secret construction bureau in Leningrad.
In 1992, he immigrated to Israel and lived in Ashdod.
Vulya Kotz died in 2015 at the age of 92.