8 Walter Jacob Gratian in his Decretum (1140), a work which became basic to canon law. Through it the“Just War Theory ” became understood as primarily based upon revealed law.’ His work listed protected classes of people which later included all non-combatants within Christendom except Jews and heretics.

Thomas Aquinas (1225-1274) considered wars justified when declared by the proper authority, when the cause was just, and when they advance the good Wars which could be designated as holy became part of Christianity ; the authority to declare such a war was vested in rulers and the pope. So Urban II proclaimed the First Crusade in 1095, as a holy war to defend the Church against Islam . Clergy were authorized to accompany the troops.

REFORMATION AND MODERN TIMES

The Reformation and the wars which it brought led to further definitions of“Just Wars ” among Protestant thinkers, so Martin Luther (1483— 1546) acknowledged the“Just War ” theory as did John Calvin (1509— 1564); both defended the rulers who acted upon it; the profession of soldier was considered legitimate despite all the bloodshed that it brought."

The inhuman Spanish policies toward the American Indians aroused considerable anger and led to the idea of placing moral limits on warfare. This was worked out in a major way by Francisco de Vitoria (1483-1546). His writings and those of contemporaries led to efforts to limit the cruelties of warfare and conquest. In Holland Hugo Grotius(1583—1645) went further and rejected religious reasons for warfare and placed war into the context of natural law. He divided natural law into those which expressed the will of God and those which are the product of human reason. War may be a“necessary evil,” but it had to be regulated. Moral laws applied to the state as well as individuals. Rational rather than religious impulses were to be determinative. Furthermore by emphasizing rules of warfare, a tradition of civilizing warfare began." The enormous loss of life and destruction caused by the Thirty Year War encouraged this new line of reasoning. These thoughts were further developed by John Locke (1632— 1704). As he lived through England’s civil war, he understood war as part of the“fundamental law of Nature.” That,