Harry was born in Vienna on 4.5.1921 to Dr. Shlomo Schneidman, from Russia, and Valle Devorah née Fischer, from Czechoslovakia.
His father was gynecologist, while his mother was a nurse in his clinic. Harry had one sister, Gerda.
He studied in elementary school and a humanist high school. Thus, he learned German, English and Italian. He learned Arabic from a medical student, a Jew from Petah Tikva, and he learned Hebrew in religious lessons in school and from a private tutor.
He was a Beitar member from age thirteen. From 1936 to 1938, he was the battalion commander of Beitar in Vienna.
On Kristallnacht, his father was arrested. He was held in a prison in Dresden for six months. His Viennese patients and their husbands secured his release, and Shlomo immediate left for Marienbad, near Prague, where his wife waited for him. Once they had certificates, in November 1939, they made aliyah.
Harry and his sister had preceded them, in September 1938, as students in the Mikveh Israel Agricultural School. After a few months, he joined the Beitar company in Be’er Tuvia. Then he established a Beitar company in Nes Ziona, becoming its first commander. He was sent to the IZL lieutenants’ course in Mishmar HaYarden. He was arrested with all the other participants, and he ended up in Acre Prison and then Mizra, under the assumed name Ari Tafran.
After the spilt, he joined Lehi. Once he was released, he set up a Lehi cell in Netanya, where the members were trained in firearms and ideology.
He still managed to get work under his real name in the British camp in Beit Lid, in an administrative camp. In 1942, he served as a translator in Camp Tel Monde for five thousand Italian prisoners, captured by the British in Africa. From 1943 until the end of the war, he worked in administration at the American vacation resort in Tel Litwinsky. He was active on behalf of Lehi among the Allied officers who visited the Land of Israel, particularly among the Jewish ones; he even brought some of them into contact with Natan Yellin-Mor (Gera), Lehi Central Committee member. He recruited supported among the Yishuv, founding a cell of industrialists and merchants in the Central region. Harry forged links with various communities for Lehi and the nascent State.
In June 1948, he enlisted in the IDF and was in de facto command of the POW camps 791 (Gelilot) and 793 (Tzrifin).
He served in the reserves until age 55, and he was the communications officer liaising with the United Nations forces in the Golan Heights.
After his demobilization in 1949, he worked in various economic capacities: in the Israel Export Union, which became the export wing of the Office of Trade; as director of development for Bank Discount; and as an investment consultant for foreign investors and trade shows for exporters. He was instrument in the building of the Validor Hotel in Herzliya, which inter alia became the location for summer camps for Jewish youth from the global Diaspora.
In 1942, he married Erica Lubitsch. They have a son and a daughter.
He wrote a play which was published in English in the United States, Ghetto Uprising.