Ptachya was born in Tel-Aviv on March 9, 1924 to his mother Leah and  father Herzl. His paternal grandfather emigrated to Israel 1881; on his mother’s side he’s descended from the Hebron Liva’ee family, living  in the country since 1800. The Zelivansky family were pioneers in Matzos industry in the country. Ptachya studied at a Commercial high-school. At fifteen he joined Etzel. After the split he joined Lehi and was active in the Youth Department, then Operations Division.

He trained in courses, participated in operations, and exhibited leadership combined with friendliness and openness to his subordinates. He was thirsty for knowledge. Following the UN Partition Resolution and  the murderous Arab onslaughts on Jews throughout the country, he fought with Lehi forces in Jerusalem. He participated in the attempt to break through to the Old City, fought to evacuate enemy forces from Lifta, Romema, Sheikh-Bader, Katamon and Sheikh-Jerach.

He commanded Lehi forces in the joint Lehi/Etzel operation at Deir-Yassin. This operation removed the danger of Jerusalem being besieged from the West. He was injured in the explosion at the Arab Legion’s  HQ at Beit-Tanus. After proclamation of the State, he enlisted  in the IDF and fought in the 8^th Brigade’s 89^th Battalion, participating in all its battles. During the 1956 Sinai Campaign he commanded the Reservist Company of  Battalion 106 in the battle of Abu-Agela. In the Six-Day War he headed the 10^th Brigade’s  commando unit.  During the Yom Kippur War he was a Commanding Officer of the Mendler Division and led his forces across the Canal under heavy enemy fire. He also participated in the War of Attrition. Ptachya married his Lehi girlfriend Yehudit Shefi and they had two children, Yo’ed and Anat, and five grandchildren.

After the War for Independence, he settled in Netanya where he owned a gas station, which became a gathering place for his friends. He later separated from Yehudit, married Esther Grinstein; they had two children, Liat and Hili, and two grandchildren. On February 25,1976, he lost his life in a car accident in Cyprus at the age of 52. He was laid to rest in Holon Cemetery.