Saint Joan is set in medieval France, which was at the time in the throes of the Hundred Years War. There are many different factions vying for power, the main ones being the English, the Burgundians, and the Armagnacs. In the play, Joan sets off on a mission from God, to make war on all those who oppose uniting France under the rule of the Armagnac, and heir to the French throne, Charles VII. Saint Joan depicts warfare as everything from a unifier to a divider to a holy right.
A Christian warrior saint is an inherently paradoxical title.
War is the only possible way to unite France. Negotiations would prove useless.