6 Av 5780 AM
Today, 603 years ago, in the year 1417, it happened to be Shabbos Chazon. Rabbi Shimon Moelin, the son of the Maharil, had his Shabbos-Spinholtz (aufruf) in Frankfurt on the Main.
This is mentioned by his father, in order to bring out that although on Shabbos Chazon according to halacha someone is not supposed to put on his shabbos clothing, the chassan and his father are exceptions. The father is allowed to wear his Shabbos cloak (overcoat), and the chassan is allowed to put on all his Shabbos clothes.
Source: Maharil, Minhagim; date and location based on I.J. Yuval, Scholars in their time, page 226, footnote 5.