Lewis and Clark By 20calamb Feb 4, 1803 Public announcment of the Lousania Purchase They told the people that they bought the Lousania Purchase. Jul 1, 1803 Preps. for the trip Made Preps. for the trip Dec 20, 1803 Lousinia Purchase Bought the Lousinia Purchase. Dec 24, 1804 Fort Mandan Fort Mandam was complete