(Wikipedia) Saint Crispin's Day is the feast day of the Christian saints Crispin and Crispinian (Also known as Crispinus and Crispianus, though this spelling has fallen out of favour), twins who were martyred circa A.D. 286. It falls on 25 October each year. It is a day most famous for battles that occurred on it: the Battle of Leyte Gulf in the Pacific theater in 1944, the Battle of Balaklava (Charge of the Light Brigade) during the Crimean War, and the Battle of Agincourt in 1415, dramatised by William Shakespeare in Henry V.
Saints Crispin and Crispinian are the Christian patron saints of cobblers, tanners, and leather workers. So celebrate by buying shoes, reading or watching the Agincourt speech from Henry V.