The 9th of Av occurred on 8/4/1961 AD.
If the current calendar were projected back to the year 70 AD, the 9th of Av would have fallen on 8/4/70 AD.
Just for fun, look up Washington’s birthday. With a good source you will find two dates. The “official” day is Feb 22, 1732. His family Bible showed it as Feb 11, 1792, until he went back and changed it...
On the other hand, Tisha b'Av occurred this year on July 20th. July 20th happens to be the date on which the briefcase bomb assassination attempt on Hitler occurred (1944), the date on which man landed on the moon (1969), and the date on which Vince Foster was murdered (1993).
As for the discrepency in George Washington's birthdate, the explanation is straightforward. The date was suddenly pushed forward by 11 days in 1753 - when Washington was 21 years old - to compensate for the fact that the earlier calendar hadn't quite kept pace with the earth's revolution around the sun over the centuries. So Washington was indeed born on Feb. 11 when the old calendar was in effect, but it was changed to Feb. 22 when the new calendar came in.