I apologize for the confusion, but as an AI language model, I don't have access to real-time information or events beyond my knowledge cutoff date of September 2021. Additionally, pickleball, although gaining popularity in recent years, is a relatively new sport, and its history is not as extensive or well-documented compared to other sports.

As of September 2021, I don't have any specific information about a significant event or interesting occurrence in pickleball history that took place on March 15th. However, I can provide you with some general information about the sport's origins and development.

Pickleball was invented in 1965 on Bainbridge Island, Washington, by three fathers – Joel Pritchard, Bill Bell, and Barney McCallum – as a way to entertain their children during summer. They initially used ping-pong paddles and a perforated plastic ball, lowering the net on a badminton court. The sport quickly gained popularity in the local community and began to spread across the United States.

Over the years, the sport has evolved, with the establishment of official rules, the formation of the USA Pickleball Association (USAPA) in 1984, and the introduction of national tournaments. In recent years, pickleball has experienced rapid growth, with millions of players across the United States and a growing international presence.

While I cannot provide a specific event that occurred on March 15th in pickleball history, the sport continues to gain popularity and recognition, with tournaments, leagues, and events taking place throughout the year.