Peter the Pilgrim of Maricourt, a French scholar, writes a letter to his neighbor, outlining his experiments with magnets and the designs for a compass and universal astrolabe.
Modern navigation will have to wait for the sextant (1757) and for Great Britain to run a contest for the most reliable mariner's clock. The winner will be John Harrison in 1765 making modern navigation possible.    
Golly! I Didn't Have a Son When I Left!
Venice merchant, Niccolo Polo returns from his visit with Kublai Khan, to find his wife dead and a son he never knew! Marco Polo is 15 years old and will accompany his father in his travels. 
The Red Badge of Courage... and Yellow
King Louis IX of France requires all Jews to wear a red or yellow badge or pay a fine. The badge is a circle of cloth and was first introduced by Muslims around the year 720 to mark Christians and Jews. A yellow badge will be used to mark all Jews in Nazi Germany. 
- "Petrus Peregrinus de Maricourt" from a Shelf3D meta search
- Houghton Mifflin Guide to Science & Technology: In the year 1269, edited by Bryan Bunch and Alexander Hellemans, 2004
- "Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time" by Dava Sobel
- "Longtitude Prize - Wikipedia"
- "Marco Polo" by Kallie Szczepanski
- 269 June 19, LOUIS IX (Saint Louis) (France)