On this day, Feb. 27, in 1859, Rep. Daniel Sickles shot and killed his wife's lover, who was the district attorney for Washington and the son of "The Star-Spangled Banner" author, Francis Scott Key.

After learning of their affair, Sickles looked out of his home in Lafayette Park and saw Philip Barton Key walk by. Sickles shot and killed Key in the park.

Papers declared Sickles a hero for saving women from Key. His attorney, Edwin M. Stanton, who later became President Lincoln's secretary of war, successfully argued that Sickles had been driven insane by his wife's infidelity.

Sickles was acquitted, the first time temporary insanity was successfully used in a murder trial.

Sickles became a Union general and lost his leg at Gettysburg.

- Scott McCabe