Recently, I was surprised to discover that Oktoberfest goes back to before the Regency. I had no idea. In fact, the first celebration was in Munich, Bavaria (now considered part of Germany) in 1810, before the official Regency period begins. It began as a celebration of the marriage of the Crown Prince Ludwig to Princess Therese of Saxe-Hildburghausen. The wine and beer flowed, and there were performances by choirs and children in costume. But the main event was a grand race of thirty horses. Those elements have been part of it ever since, along with other typical festival events, and it’s been canceled only twenty-four times out of the 209 years it’s been held (for example, it was cancelled in 1813 because of the Napoleonic wars, and in 1854 due to a cholera epidemic). So you would be perfectly at home if you celebrated Oktoberfest in your Regency costume!
