Black Death

The plague took over 20 million lives in a period of two years
The microorganism Bacillus pestis was the main cause of the plague.
The plague was carried in the bloodstreams of rats and of insects that fed off of their blood.
Bodies infected by the plague were launched in catapults to get them out of the city. If the rotting bodies stayed around for too long other people could meet their death the same horrible way.
This was only a temporary solution as the bodies soon infected the water supply and the city became infected.
Ships that brought over imports to Europe had rats in them. Rats that were infected with the Black Death. The encounters, however brief, were enough to infect Europe.
All contact made with anyone who died of the plague died shortly afterwards.
The plague was thought to be a sign from God and no one dared to question His ways
The sickness lasted three days and by the fourth day the patient was dead.
People's reactions were of fear. They now believed that God was now angry and the end of the world was near.
Burial areas were no longer available and there were so many deaths that corpses had to be laid out in the city.
From Cicily the plague reached the mainland and covered the land in the stench of the plague.
The plague was steadily making its way to France's palace and the royalties were beginning to get frightened.
Philosophers suggested that fire would cleanse the plague-riddled air and when the plague had all but reached the palace massive fires were erected and this did indeed quench the problem for quite some time. But it offered no protection for the common man. Humans continued to die by the thousand.
Eventually the one they were protecting fell ill with the plague, but he worked to heal himself and prevailed. He sought to find an actual cure and after he did he allowed himself to be present at blessings of the dying.
Jews were accused of polluting the water and were massacred in great, only adding to the number of deaths that was still growing exponentially.
By 1350 the plague was over in Europe but left horrible scars in its wake.
After all of these events people had more belief in God but cared less for the actual established Church.