Army officer who shot and killed Philip Barton Key, son of Francis Scott Key, because of Key's attentions to Mrs. Sickles. He was tried and acquitted on the grounds of a then-novel plea of a temporary mental aberration; he later became a Union general and lost a leg in defense of the famous Gettysburg Peach Tree salient. ALS signed 'D. Sickles,' one page both sides, 5.25 x 8, November 1, 1873. Letter of thanks and congratulations to General Lew Wallace. In part, 'I ...received your letter of the 13 accompanying a superbly bound copy of your Romance in ready...My daughter has it already.' In fine condition, with small tear along mailing fold, light toning and some mounting remnants to left edge. RRAuction COA.