Yuval Ne'eman joined the Haganah at age 15. During the War of Independence he served as deputy commander of a battalion, operations officer in charge of Tel Aviv and as deputy commander of battalion #51 in the Golani Brigade. Afterwards he was appointed head of the Operations Branch under the leadership of Yitzhak Rabin, in charge of the Department of Operations.
At the end of 1954, after Benjamin Gibly was relieved of his job as head of "Aman" following the "Esek Bish" episode, Ne'eman was temporarily appointed in his place and continued as deputy to Yehoshafat Herkevi.
As colonel, Head of Defense Planning, he laid the foundations of Israel's mobilization system and crystallized the strategic conception prevailing until 1967 and tested in the Six Days War.
During "Operation Kadesh", he coordinated military cooperation with England and France. Afterwards, Ne'eman was responsible for contact with the Kurds in Iraq and other Jewish communities in the Islamic countries. In 1958, he was named military liaison officer in London, and dedicated himself to earning his doctorate in physics. In 1961 he was discharged from the army.
After the Yom Kippur War, he was acting head of "Aman" for a short time following the dismissal of Eli Ze'ira. In addition, he was involved in checking out the intelligence failures that occurred during the war. In the 1970s he was an advisor to Shimon Peres in the Defense Ministry.