The Western Schism was one of the most traumatic events suffered by Christendom during the Middle Ages and was at least one of the reasons for the eventual outbreak of Protestantism in the years to come. For some years the Popes had left behind the crime and pestilence of Rome to settle in the Papal city of Avignon in France. A succession of French popes were elected and this period, which so angered the Italians and the Romans in particular, was referred to as the “Babylonian Captivity”. Pope Gregory XI was finally persuaded by St Catherine of Sienna to return to Rome but only a little more than a year later died in 1378. It was hardly a good omen for the assembled cardinals, mostly French, who were very nervous about being back in Rome to begin with and anxious to return to Avignon. Tensions increased when the Sacred College gathered at the Vatican were surrounded by an angry Roman mob demanding that one of their countrymen be elected. The choice was finally made, though it was a Neapolitan rather than a Roman, and Pope Urban VI was elected.
Once back in Avignon, however, the cardinals said they had acted under duress and that the election was invalid and promptly elected another cardinal (French this time -Robert of Geneva) who took the name and title of Pope Clement VII. Soon all of Europe was divided into two camps; pope and anti-pope, both disagreeing on which was which. England, Denmark, Sweden, Poland, Hungary and the north Italian states sided with Pope Urban VI. France, Spain, Naples and Scotland sided with Clement VII with Portugal and the German Holy Roman Empire shifting between the two. Today, historians can look back and judge dispassionately who the pope and who the anti-pope were, however, at the time it was no simple matter. Both had arguments in their favor. Surely a decision made under threat could not be valid, yet just as surely there would be perpetual chaos in Christianity if cardinals could ‘take back’ their decision once a pope had been elected and accepted the throne.
One of those who first welcomed the election of the Neapolitan Pope Urban VI was of course Queen Joan I of Naples. However, Urban (the legitimate pope but a rather unsavory character) turned against the Queen and declared her deposed and absolved her subjects of their allegiance to her, joining in common cause with her primary enemy Charles Durazzo, later King Charles III. At this time, during a period of Genoese triumph over Monaco, Lord Rainier II has Queen Joan I as his own overlord in the feudal hierarchy of the time. As was to be expected, Rainier II was then also originally on the side of Pope Urban VI, in fact when the French cardinals fled Rome to return to Avignon and elevate another pope, Rainier II had actually taken some of the rebel cardinals prisoner in Menton (the seat of Grimaldi power since the Genoese had exiled them from Monaco in 1357). However, things began to change when Queen Joan angrily removed her rival Charles of Durazzo from the succession and proclaimed Louis of Anjou as her heir. In retaliation Pope Urban VI had Charles crowned King of Naples and preached a crusade against Joan I.
This put Joan I and the Kingdom of Naples firmly in the French camp of Anti-Pope Clement VII (Louis of Anjou being the younger son of the King of France) and Lord Rainier II along with them. However, Charles III quickly moved to invade Naples with Pope Urban VI elevating it to the status of a crusade and declaring Joan a heretic. The forces led by her husband were few and no match for Charles III who was soon victorious and had Joan (his cousin) imprisoned and finally murdered in 1382. Rainier II had not forgotten Queen Joan and a fleet of galleys from Provence (from whence came the ties between the Anjou house of Naples and the Grimaldis) were dispatched to her aid but they did not arrive in time. In time the Pope and Charles were enemies as well and, several years after the death of Joan, Pope Urban VI died, legitimate but distrusted and unpopular, in 1389. Clement VII lived on until 1394 but Lord Rainier II survived them all, going to his eternal reward in 1407.