It was a Thursday.
March 21, 1966 was the 3rd Monday in March for that year.
That date can be interpreted two ways: The 3rd of September 1966 was on a Saturday. March the 9th 1966 was on a Wednesday.
22 March 1966 was a Tuesday.
March 6, 1966 was a Sunday.
March 11, 1966 fell on a Friday.
31st March 1966 was a Thursday.
March 16 1966 was on a Wednesday.
5 March 1966 was a Saturday.
March 13, 1966 fell on a Sunday.
March 7, 1966 was a Monday.
March 25 1966 was a Friday.
March 1st was on a Tuesday in 1966.