October 21 is the 294th day of the year in the Gregorian calendar, with 71 days remaining until the end of the year. It is often associated with the changing of seasons, as it falls in the middle of autumn in the Northern Hemisphere. Historically, several significant events have occurred on this date. For example, in 1805, the Battle of Trafalgar took place, where the British Royal Navy, led by Admiral Horatio Nelson, defeated the combined fleets of France and Spain. Additionally, October 21 is celebrated as National Reptile Day in the United States, promoting awareness and conservation of reptiles.