General fact: 715 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Mathematical fact: 715 is an unremarkable number.
Trivia: 715 is an unremarkable number.
Historical date: December 15th is the day in 1467 that Stephen III of Moldavia defeats Matthias Corvinus of Hungary, with the latter being injured thrice, at the Battle of Baia.