The renewal of Jewish sovereignty in 1948 created a grave challenge to Jewish tradition. As a system that was constructed in exile for a non-sovereign society, Jewish law was lacking "laws of state." The legitimacy of military action and the distinction between just and unjust wars are prime examples of fundamental issues that Jews did not have to confront for a very long period of time. This article examines contemporary Jewish legal responses to the challenges posed by the creation of the Israeli military. It focuses on the efforts of Rabbi Shlomo Goren, the first Chief Rabbi of the Israel Defense Forces, to create a modern corpus of Jewish law and ethics relating to war and the military. The Diaspora-based rabbinic literature seemed to oppose the use of force, reinterpreting Biblical references to military heroism as allegorical expressions of valor in the study of Torah. In an attempt to create an approach that legitimized the use of force while, at the same time, maintaining the rabbinic moral compunction regarding reliance on force, Rabbi Goren’s innovative corpus integrated Biblical and rabbinic sources, as well as pre-rabbinic apocryphal and historical sources. His writings on the subject are studied on a historical level, trying to uncover the various personalities and ideological positions to which he reacted. Rabbi Goren’s approach is examined through an analysis of his views on the proper treatment of the enemy and on the Peace for Galilee War in Lebanon. He advocated a balance between power and spirit, a balance that is also reflected in the personal internal harmony of Rabbi Goren himself: a merger of two worlds — the traditional student of the rabbinic study hall and the modern Jewish military officer — worlds by which he was influenced, between which he was torn, and that he tried to synthesize.