In the spring of 1946, at the age of seventeen, Etzioni dropped out of high school to join the Palmach, the elite commando force of the Haganah, the underground army of the Jewish community of Palestine, and was sent to Tel Yosef for military training. When the Palmach learned that the British police had captured a list of the Palmach members, they were issued new, fake ID cards and had to choose new last names. Amitai Falk chose "Etzioni", a pen name he had used when he started writing in Ben Shemen at age 15.