after joining the israel defense forces, shafir completed an officers' course and served as an instructor at the officers academy. in 1950 he was discharged from regular service in the army and began serving as an infantry company commander with the reserves. that same year, at the age of 21, he became the first reserve officer to complete the battalion commanders course. he returned to permanent service the following year and was appointed operations officer of a reserve brigade. between 1951 and 1952 he served as the operations officer of southern command and commanded a reconnaissance company. after transferring to the armored corps, shafir led an armor company and went on to become the corps' operations officer. during the 1956 sinai war, shafir was the operations officer of the 77th division.