It's ironic that was so daunted by the idea of playing President Abraham Lincoln that he initially turned down the role, considering he played the famous President with such grace and realism in Lincoln that he has actually helped shape the course of U.S. history.
How? Well, fun fact for all you history buffs; somehow, Mississippi never actually got around to ratifying the 13th Amendment. You know, the one that legally abolishes slavery.
The Jackson Clarion Ledger reported (via Cinema Blend) how two university professors, and one Hollywood movie, helped change the history of their state. When University of Mississippi associate professor Ranjan Batra finished viewing Lincoln, he was so inspired by Day-Lewis' portrayal of Lincoln fighting to get the 13th Amendment passed, that he did some research into his own state's history on the Amendment and lo and behold, discovered that Mississippi had never officially ratified it and that it was, in fact, the only state at the time (there were 36) to not ratify it. The good news for Mississippi is that it did actually get around to passing the bill in 1995 (hey, 130 years later is better than nothing, right?), but the state somehow never got around to notifying the U.S. Archivist about passage of the bill, so the vote was never made official.
Batra reached out to his friend and colleague, Ken Sullivan, to help. Sullivan then went to the theater to see Lincoln for himself and was completely moved to tears. "I felt very connected to the history," explained Sullivan. So, he contacted Mississippi Secretary of State Delbert Hosemann and asked him to file the necessary paperwork. On February 7, Hosemann received a confirmation from Charles A. Barth, director of the Federal Register. “With this action, the State of Mississippi has ratified the 13th Amendment to the Constitution of the United States,” it read.
While this doesn't come anywhere close to the reality Abraham Lincoln went through when trying to get the 13th Amendment passed, it's still a pretty cool story. I'm guessing , Day-Lewis, and the rest of the cast are feeling good about things - it's not every day you help shape, in some small way, the course of history.