After substantial discussion over the last few months on this board and several overhauls, I've come up with a revised outline for a timeline that's been in the works since 2007. The goal of the TL was (and still is) to show what the world could have been like if Christian European civilization was destroyed prior to the extensive exploration and colonization which began in the 1400s. (Hence the title, The Heirs to History.) The trick was finding just the right cause for this without resorting to ASBs or handwaving. My original plan was to have a mutated form of the Black Death devastate Europe far more than the rest of Eurasia, but this was shot down by science. My second plan was to have an asteroid impact in Greenland melt enough ice to disrupt the North Atlantic Current and have Europe hit with several bad winters during the Black Death; this was similarly shot down as unfeasible. By that point, I was beginning to feel mildly discouraged.
Thus, with considerable and invaluable assistance from Falastur, I eventually arrived at Plan C: The Papal Wars. What follows is a summary of what I've got so far. The POD is Pope Clement VI dying of the plague in 1348 rather than of natural causes in 1352. Because this is during the worst of the Black Death in southern Europe, several cardinals die of the plague en route to Avignon to select a new pope and on the way back home. Innocent VI is chosen as in OTL, but unfortunately also succumbs to the plague shortly after his election. Understandably hesitant to make the journey to Avignon again, the remaining and newly-promoted cardinals collectively decide to delay another Papal Conclave until the plague has passed.
As news of this controversial decision spreads, many Christians feel bereft of spiritual leadership. In Paris, King Philip VI unilaterally decides to appoint his own choice of pope in Avignon anyway. Naturally enraged by this hasty and presumptuous decision, the Papal States, with the support of the Holy Roman Emperor Charles IV, place a new pope in Rome, claiming that he is the true pope, not the imposter in Avignon. The Holy Roman Empire (HRE) is not united in this decision, and a doctrinal council is established in Nuremberg by more conservative elements within the HRE. Also infuriated by France's papal appointment, English king Edward III sets up a doctrinal council in London to question the Avignon pope's every decision. The ongoing conflict between England and France (the beginning of the Hundred Years' War) escalates as the opposing armies redouble their efforts. Scotland provides the French with military assistance by opening up an additional front in northern England.
Other Christian states in Europe seek their own solutions to the problem. Fed up with the controversy over the Rome and Avignon popes, Castile appoints a third pope in Burgos and presses Portugal to accept this pope as the true one. When Portugal refuses, war breaks out in Iberia. Aragon allies with Portugal against the rival Castile. In Hungary, belligerent king Louis I selects his own papal appointee and attempts to supplant the Rome pope by force. Assisted by subtle prodding from the Teutonic Order, the Holy Roman Empire fragments in a civil war between supporters of the Emperor's choice of pope in Rome and the Nuremberg council. Poland seeks a resolution to the conflict, but remains for the most part neutral, as do Denmark, Norway, and Sweden.
There's much more, but before I proceed, I'm looking for some (constructive) criticism on this summary. Is what I have so far plausible?