The conflict in Saint Joan is built around some pretty major power clashes. The Catholic Church and the English feudal lords are all challenged by Joan's rise. Her allies desert her for fear of losing the power she has helped them gain. In the end she is crushed by all of these converging forces. Saint Joan could be viewed as a case study on the disturbing lengths people will go to in order to maintain and gain power.
Joan is crushed between the two great powers of her time – the Church and the Aristocracy.
Joan's Nationalistic urge to centralize power with the King, threatens to upset the feudal structure of her entire society.