It is a proper noun, as it is referring to a specific named day.
yes
the St. valentines day massacre happened on February 14, 1929
St valentines
It was on a Thursday.
St Valentines day
Saint Valentine's Day 1929
Al Capone orchestrated the St. Valentine's Day Massacre
Yes, it is the proper way to do it. It would be St. Patrick's Day.
14th Febuary 1929 §♥
February
1929
Valentines day wasn't invented actually it was a person. He was a person who gave love to the world and this is the day we celebrate it.