The Louisiana Purchase was a big deal. (Read more about the ins and outs of it in this post: http://www.historynaked.com/the-louisiana-purchase/) It was a great deal for the United States, but it was somewhat of an administrative nightmare. The territory being turned over was huge. Also, it technically belonged to the French as part of a secret treaty with the Spanish in 1769. However, since the Third Treaty of San Ildefonso was secret, Spain still administered the territory to keep up appearances. Confused yet? So were a lot of other people. Many of the Spanish officials didn’t know they were working for the French until it came time to turn things over to the Americans.
The official turnover to the United States was on April 30, 1803. However, paperwork and logistics were slow and the process dragged into the summer and fall of 1803. Money finally changed hands and that winter, there was an official ceremony in New Orleans, which was the capital of the territory. One problem. Because it was winter, there wasn’t much travel going on and the news didn’t filter northward. St. Louis was a growing city, both in population and importance. They didn’t get the word they were Americans until March 1804. An even bigger problem was the city was still in Spanish hands, many of whom didn’t know they were technically working for the French. It was decided to take the bull by the horns and implement both treaties in the space of 24 hours. A notice was posted by the Spanish governor of St. Louis, Carlos de Hault de Lassus, on March 8, 1804 notifying the citizens about the impending changes.
On March 9, 1804, the ceremonies began in front the governor’s mansion and a small crowd. De Lassus and the US Army representative, Amos Stoddard, signed a sheaf of papers. Then De Lassus spoke to the crowd, “By order of the king I am now about to surrender this post and its dependencies. The flag which has protected you during nearly 36 years will no longer be seen… From the bottom of my heart I wish you all prosperity.” At his words the flag of Spain was slowly lowered and the flag of France rose in its place. The French flag was only supposed to fly for a total of six hours, but St. Louis had originally been a French town and many of the citizens remembered their roots. There was a cannon salute and a huge party. Who doesn’t love a party? So the Americans allowed the French flag to fly until noon the next day. People gathered in the church and sang French songs and generally had a great time. At noon March 10, 1804, the French flag was lowered and the stars and stripes took its place. France had declined to send a representative to sign over St. Louis, so it was agreed Stoddard would sign for both countries.
The day has been commemorated as the Day of the Three Flags. The event was reenacted at the corner of First and Walnut streets in St. Louis, MO, site of the original ceremonies in 1804, in 1935.