Answer:
To Protect them from the Red Death Plague
Step-by-step explanation:
Consider the except below from Masque of the Red Death by Edgar Allan Poe.
"The “Red Death” had long devastated the country. No pestilence had ever been so fatal, or so hideous... But the Prince Prospero was happy and dauntless and sagacious. When his dominions were half depopulated, he summoned to his presence a thousand hale and light-hearted friends from among the knights and dames of his court, and with these retired to the deep seclusion of one of his castellated abbeys...A strong and lofty wall girdled it in. This wall had gates of iron. The courtiers, having entered, brought furnaces and massy hammers and welded the bolts....With such precautions the courtiers might bid defiance to contagion. "
As can be seen in the except from the opening paragraph of the book, Prince Prospero invites one thousand of his friends to the abbey in order to protect them from the Red Death which has attacked the Prince's country.