August 13, 1976 was most certainly a Friday. (Boo!)
August 13, 1959, was a Thursday.
August 13, 1990 was a Monday.
August 13 1999 was a Friday.
August 13, 1960 fell on a Saturday.
August 13, 1963 fell on a Tuesday.
Thursday
13th, August, 1966, was a Saturday.
It was a Friday.
Saturday
This varies from year to year. The 13th, August, 2010, is a Friday.
The given date was a Saturday.
August 13, 1521, at The Fall of Tenochtitlan (present-day Mexico City).