1865: Robert E. Lee is named the Commander-in-Chief of the Army of the Confederate States of America.
1952: George VI, BTGOG, of Great Britain, Ireland and the British Dominions beyond the Seas King, Defender of the Faith dies in his sleep, and is succeeded by Elizabeth Alexandra Mary: Queen Elizabeth II
1971: Apollo 14 commander Alan Shepard becomes the first (only?) person to hit a golf ball on the moon.
2008: xyon wears 30" pants for the first time since time immemorial.
Pick your favourite least-important one. Personally, I think it's the 1952 entry.
1865 is funny since the war was over 3 months and 3 days later.