Gravi de pugna

Gravi de pugna is a forged letter written in the name of Augustine of Hippo which argues that just wars are the ones you win. The letter was widely accepted as authentic, and reassured soldiers that God was on their side.

Ideology
Gravi de pugna is best known for its simple assertion that God will assure that the morally superior side will win military battles, and conversely, that victory itself validates that the use of force was appropriate. Udo Heyn claims this was a Germanic notion, and Phillip Wynn reports that it had long been believed in pagan antiquity by the time of this letter. This understanding was, in fact, utterly rejected by Augustine. Kelly DeVries regards the theology of Gravi de pugna as shallow and considers it to raise problems of theodicy and legitimacy as soon as the first Christian army loses.

Gravi also urges prayer for victory before battle, which was also rejected by Augustine, who found such prayers inappropriate.

History
Gravi de pugna was written in the fifth century. The letter was widely accepted as authentic from its introduction through the medieval era, and was the most frequently cited text in this period on holy war. It was invoked to justify numerous wars, including by Hincmar of Reims, Rabanus Maurus, Sedulius Scottus, Ivo of Chartres, and Bernard of Clairvaux It was also recited at the Siege of Lisbon in. Gravi imbued the Crusaders with confidence that God was on their side, squelching all moral concerns and leading to behavior that did not comply with then-accepted rules of war.

The work lost influence with the renaissance of the 12th century, which developed more sophisticated jurisprudence and moral reasoning, At the same time, Augustine's own opinions, which had been largely unknown, were studied by the decretists and though them, Aquinas as well. The authenticity of Gravi de Pugna was not conclusively rejected until Erasmus. Although it is regarded by contemporary scholars as "obviously un-Augustinian", it is now widely recognized that Gravi de pugna has inaccurately influenced scholars of Augustine's views on war even up through modern times.