Should you forget to get innoculated before you travel back to the 14th century, you'll need to take some measures to avoid the deadly Bubonic Plague.

Difficulty: Hard
Time Required:  variable

Here's How:

1. Keep some clean clothes tightly folded and bound up in cloth treated with pennyroyal, preferably in a cedar chest far from all animals and vermin.
2. At the first whisper of plague in the area, flee any populated town or village and head for an isolated villa, far from any trade routes, with your cedar chest.
3. Vigilantly clean every last corner of your villa, killing all rats and burning their corpses.
4. Use plenty of pennyroyal to discourage fleas.
5. Allow no cats or dogs to come near you.
6. Once away from all human contact, wash in extremely hot water, change into your clean clothes, and burn the clothes you traveled in.
7. Keep a minimum distance of 25 feet from any other human being to avoid catching any pneumonic form spread through breathing and sneezing.
8. Have your armies burn and raze to the ground any nearby houses where plague victims have resided.
9. Pray to the deity of your choice frequently and fervently.
10. Stay where you are until six months after the most recent nearby outbreak.

Tips:

1. Do not enter an enclosed community such as a castle or monastery.
2. Do not under any circumstances board a ship.
3. If possible, try to establish your residence in Bohemia before 1347, and don't leave until long after 1353.

More How To's from your Guide To Medieval History