Yoseph was born in 1913 in Rosh Pina to Shmuel and Rachel Horovitz. His father was an agronomist sent to Eretz Israel by Baron de Rothschild to assist in the olive plantations in the moshava. Yoseph was the twelfth and youngest child in the family. He studied in the local Hebrew School and at the age of 14 founded, together with a few of his friends, the local Beitar cell. He finished his studies with distinction and was sent to Jerusalem to study at the Mizrahi Seminar for teachers. He was one of the first to join Abba Achimeir’s Brit HaBiryonim. He was young, talented, and good-looking. He participated in the demonstrations against closing the gates of the country to immigrants and headed a group of youngsters who threw bricks at the police officers that came to disperse them. He was arrested and sentenced to prison with hard labor in the notorious Nur Shemesh Camp near Tul Karem. Yoseph refused to wear the prisoners’ uniform and was whipped and tied to a poll with his head hanging down. The Arab prisoners admired him for his bravery and called him Yusuf Effendi.
In 1937 he returned to Rosh Pina after his release and established the local National Defense branch, which shortly afterwards became known as Etzel. He was uncompromising concerning everything to do with the Hebrew struggle against the British Mandate. When Etzel split he followed Yair and became one of the Lehi commanders in the Tel Aviv region, and later the commander of the Jerusalem branch. He spent lengthy periods in prison.
Towards the establishment of the State he was sent to Europe on a weapons acquisition mission and went from Prague to Italy. Having worked in a quarry in the Galilee he used his experience to smuggle weapons into Eretz Israel in barrels of gypsum.
After the State was established and Lehi was disbanded he returned to the moshava where he was born and devoted himself to the tasks of developing an apple tree plantation and taking care of his land and his father’s olive tree plantation. He was a member of the local council for many years and spent most of his time establishing projects and involving himself in the welfare of the inhabitants. During all the years of his underground and public activities he had not found the time to get married.
He was very friendly with Nathan Yelin-Mor and identified with his efforts to find a compromise with the Arabs. He passed away on March 11, 1980. Before his death he received the Lehi and also the Aleh Decorations, which pleased him greatly because he felt it was a fitting reward for the years he had dedicated to the establishment of the State.