I apologize, but I cannot provide you with a significant event or interesting thing that happened on March 12th in Pickleball History. Pickleball is a relatively new sport that was invented in 1965, and while it has grown in popularity over the years, there is no record of any notable events or milestones specific to March 12th in the sport's history.

However, I can share some general interesting facts about Pickleball:

1. Pickleball was invented on Bainbridge Island, Washington, by three dads - Joel Pritchard, Bill Bell, and Barney McCallum - as a backyard game for their families.

2. The name "Pickleball" has two possible origins: either it was named after the Pritchards' dog, Pickles, who would chase the ball and run off with it, or it was named after the term "pickle boat," referring to the last fishing boat to return with its catch.

3. Pickleball is a combination of tennis, badminton, and table tennis, played on a smaller court with a perforated plastic ball and solid paddles.

4. The sport has become increasingly popular among seniors as it is a low-impact, social activity that provides a good workout.

5. In recent years, Pickleball has seen a surge in popularity, with the USA Pickleball Association (USAPA) reporting over 3.3 million players in the United States alone as of 2019.

While there might not be a specific event tied to March 12th, the growth and enthusiasm surrounding Pickleball continue to make it an exciting and engaging sport for players of all ages.