It depends. US: He wore a wool suit on the third of April. or He wore a wool suit on April 3rd. or He wore a wool suit on the 3rd of April. or He wore a wool suit on April 3. (this isn't wrong, but I would prefer writing "April 3rd" and I would read this as "April third" not "April three.") If he decided to wear a wool suit in the middle of the summer, I would write: He wore a wool suit on the Fourth of July. But I would only capitalize "Fourth" because that day is a fairly significant US holiday that we refer to by the date. If it were almost any other day (e.g., third of April, twenty-fifth of December, first of January), I wouldn't capitalize the number.

British English: on July the fourth /on the fourth of July American English : on July fourth However, I am British and so am not an authority on American English.

Hi there, You could express your sentence in these ways: He wore a wool suit on the Fourth of July. He wore a wool suit on July 4th. Good luck with your studying !