The Cadaver Synod, no doubt the most bizarre episode amidst a papal history studded with strange events, was a product of political hardball, not a question of arcane rules of papal succession. That, and Pope Stephen VI must have been a nutjob.

It all starts with the collapse of the Holy Roman Empire under Charles the Fat in 887. That meant the Vatican had to fend for itself just like any other European fiefdom. What made the Vatican a sought-after prize was that the Pope traditionally crowned the Holy Roman Emperor, starting with Charlemagne's crowning by Pope Leo III in 800. Sure, there was essentially no more empire, but who wouldn't want the title of Holy Roman Emperor, especially when it was conferred by God's spokesman on earth?

Pope Stephen V's first choice was the Frankish King Arnulf, but he apparently had a prior engagement, so Pope Stephen V enlisted the help of Guido III of Spoleto to defend Rome from pagans and such. Guido was paid off by being crowned emperor. Upon Stephen's death, Formosus was named Pope, but Guido had doubts about a famous troublemaker like Formosus, and demanded he be crowned emperor again and his son Lambert be named heir apparent and co-emperor. Formosus consented.

But when Guido died in 894, Formosus made a deal with King Arnulf. Arnulf kicked the Spoletans out of Rome and was crowned emperor, and Lambert was sent packing. But the emperor's reign didn't last because Arnulf was paralyzed and soon died. When Formosus died in 896, the new pope, Boniface VI, lasted only fifteen days before dying. Either it was gout or he was murdered to make way for Formosus' rival, the new Pope Stephen VI. Hearing the news, Lambert and his troops marched back into town and Stephen crowned him emperor.

Why the repulsive extravagance of the Cadaver Synod? Perhaps Stephen was trying to impress Lambert, or he may have been under orders from Lambert and his mother, Ageltruda. Either way, Stephen didn't last long. During the Synod, an earthquake struck Rome and destroyed the basilica, a very bad omen for him. Also, Rome was rife with rumors that the corpse of Formosus was performing miracles. Formosus' posse seized the opportunity and arrested Stephen, and he was later strangled in prison.

BTW, the multiple Stephen problem does not stem from missing popes. Stephen II died three days after he was elected in 752, before he was consecrated. Back then, unconsecrated popes were not considered popes, but in the 16th century the Church reversed this decision and returned Stephen to the official list of popes, which screwed up the numbering for all the popes since 752 who had taken the name Stephen.

Sources: britannica.com; The Catholic Encyclopedia; John Dollison, Pope-Pourri