Examine the evolution of the concept of a just war from Marcus T. Cicero to Thomas Aquinas

The idea that a war can be morally justifiable can be traced back as far as ancient Egypt. As a philosophical concept, it finds its origins in Ancient Rome. In 44 BCE, Marcus Tullius Cicero defined the term in one of his final writings, De Officiis. With the Republic crumbling around him, Cicero wrote this piece in an attempt to define public morals. Cicero argues that war is not the mark of a civilized nation and therefore must only exist as a last resort. For a war to be just, an official warning must be issued to one's enemies first, so that there can be one last chance to avoid conflict. Furthermore, according to Cicero, war must only be waged in order to secure peace, and punitive measures over the losing side must not be made too harsh.
Saint Augustine of Hippo amended the notion of a just war in Christian terms in the 4th century. Like Cicero, Augustine argued that war should be avoided if at all possible. However, he went on to posit that a government of Christians had God's tacit permission to defend themselves with the sword and to punish sin and wickedness through the use of violence. Bloodshed committed in the name of God, he argued, did not violate any divine commandments.
In the 13th Century, Thomas Aquinas sought to combine Augustine's notion of a religiously justified war with the philosophical notions of reason as laid out by Aristotle and other ancient philosophers. In Summa Theologica, he contends that reason and theological revelation are not contradictory. When concerning war, they come together to determine if a conflict is justifiable. First, a war may not be fought for self-serving reasons, such as the acquisition of territory or for vengeance. Wars must be declared and waged under the state's authority only, since the state represents both the people and the will of God. Like Cicero, Aquinas argued that a just war must be waged with peace as its final goal.
http://faculty.georgetown.edu/jod/augustine/civ.html

https://www.christianitytoday.com/history/people/theologians/thomas-aquinas.html