Abraham Lincoln was a terrific trial lawyer before he became a terrific president. In his most famous case, he defended William "Duff" Armstrong on a murder charge. The year was 1858, at a time when trial lawyers only used witness testimony to prove their cases. Other types of evidence commonly used today, like scientific data, were a novelty then.

Lincoln left his town of Springfield, Illinois for Beardstown to defend Duff, the son of an old friend, now dead. The entire case against Duff rested on the testimony of one man. Charles Allen, the eyewitness, said there was a full moon the night of the murder. At about 11 pm, from 150 feet away, he saw Duff kill James Metzler. The prosecutor thought he had an air-tight case. During Allen's testimony, Lincoln stared at the ceiling, unimpressed and bored.

When he rose to cross examine Allen, Lincoln made a motion to use an 1857 almanac. Judge James Harriot allowed this new type of evidence to be used. Lincoln made Allen read the almanac entry for August 29, 1857 - the night of the murder. The truth finally came out of Allen's mouth: There was no full moon that night. In fact, there was no moon at all at 11 pm.

Believing the almanac, not Charles Allen, the jury found Duff not guilty. Lincoln, who would be president just a few years later, had predicted an acquittal by sundown. He was right.

Lincoln handled the entire case without a fee.