Philip IV vs Pope Boniface VIII

From author Andrew Latham:

In the late 13th century, the French king, Philip IV, began taxing members of the French clergy in order to help finance his war against England.  While formally prohibited by a decree of the Fourth Lateran Council, the papacy had long acquiesced in the practice of French lay rulers taxing their clergy without explicit papal authorization, largely because it depended on French support in its perennial conflicts with the Holy Roman Emperor.  In 1296, however, Boniface decided to apply the prohibition to France as well as the Empire.  Historians disagree as to why he made this fateful decision.  On the one hand, there are those who assert that the new pope was simply acting on the basis of his firmly held hierocratic belief that ecclesiastical power was superior to temporal power.  On this view, Phillip’s decision to tax the French Church presented Boniface with his first real opportunity to assert ecclesiastical authority – an opportunity he seized enthusiastically. (Read more.)