Naphtali was born on November 19, 1913 in Moscow to Eliezer and Olga. After the 1917 revolution, the family moved to Riga, where he finished his high school studies and traveled to study history and economics in Germany. He was active in Zionist students’ organizations. When Hitler assumed power in 1933, he put a halt to his studies and made aliyah with his wife Lana. He studied linguistics in Jerusalem’s Hebrew University while he worked for the Lloyd Triestino company in Tel Aviv. Naphtali was part of the Revisionist Movement, and he was wisely concerned to hold extreme views within it. In 1939, he joined IZL, and the command staff gave him orders to quit his civilian job and to dedicate himself to underground work. First, he was in charge of the finances. He was very impressive and respectable in his appearance, spoke seven languages and was capable of benefiting the underground in the most senior positions.

When IZL split, he followed Yair. He quickly earned his trust and was sent on a delicate mission to Beirut, which was ruled by France’s Vichy government. The proposal to Berlin and Rome was that Lehi would continue fighting the British, while they would realize the rights of the Jewish people to a state and help transfer Europe’s Jews to the Land of Israel. However, Lebanon was captured by the British, and Naphtali was captured in 1941, before he could carry out his mission. He was returned to the Land of Israel and imprisoned in Mizra. Then he was transferred to Acre Prison and kept for three years in solitary confinement. Nevertheless, his spirt was not broken: he used his time to study Hebrew and the Bible. He was among the first group of 251 who were exiled to Africa on 19 October 1944.

He was kept in Sembel (near Asmara, Eritrea), Carthago in Sudan, and once again in Eritrea. Naphtali suffered from gastrointestinal disease, and while he was still imprisoned in Acre, he was hospitalized in Haifa. His illness worsened while he was in detention and he was hospitalized again, but he was treated by an inexperienced doctor and asked them to take him back to the camp. When he felt that his end was near, he said to his friends: “If something happens to me, I want you to take my bones back to the Land.” He died on 20 April 1946 in a military hospital, after much suffering amid five years of imprisonment in the Land of Israel and in exile.

His bones were brought to the State of Israel in 1949 and interred in Jerusalem, together with the bones of Shaul HaGelili and Eliyahu Ezra, who were killed on January 17,1946 by Sudanese guards in Eritrea. He left a wife, Lana née Weiner.