Apparently, Abraham Lincoln himself never knew that he was carrying a secret message inside his pocket. The message that you can see in the picture was engraved inside of his watch, and this is its story:
Doug Stiles, great-great-grandson of watchmaker Jonathan Dillon, corroborated a story that had been passed down for generations in the Dillon family. Here’s how the story went: Jonathan Dillon was working for M.W. Galt and Co. in 1861 when the owner of the shop announced that the first shot of the Civil War had been fired at Fort Sumter. In an interview with the New York Times, published on April 30, 1906, Dillon recalled that the news inspired him to unscrew the dial of President Lincoln’s watch, which he had been busy repairing, and with a sharp instrument he wrote on the metal beneath: “The first gun is fired. Slavery is dead. Thank God we have a President who at least will try.” To his knowledge, Dillon told the Times, no one else had ever seen the inscription. When Stiles contacted curator Harry Rubenstein about the tale, the museum agreed to remove the watch dial to see if it was true.
And this is what happened: