September 1st 1940 was a Sunday.
17 September 1940 was a Tuesday.
September 12 1940 was a Thursaday
September 23 1940 was a Monday.
September 20, 1940 fell on a Friday.
September 3rd, 1940 fell on a Tuesday.
19th September 1940 fell on a Thursday.
May 1st, 1940 fell on a Wednesday.
September 1st, 1965 was on a Wednesday.
September 1st 1969 was a Monday.
September, 1st, 1956, was a Saturday.
1st, September, 1729, was a Thursday.
September is a whole months, so it couldn't have fallen on any day of the week. The first day of September (in 1994) was on Thursday, and the 30th was on a Friday.