On this date in...
1782: George Washington authorized the Badge of Military Merit, a cloth badge worn on the facing of the frock coat. It was purple in color, shaped like a heart, and awarded for valor. It wasn't until 1932 that the Purple Heart evolved into its current form as an enemy marksmanship medal.
1789: The bellicose-sounding U.S. Department of War was formed. It wasn't until 1949 that the name was changed to the (much less offensive to sensitive types) "Department of Defense". Hippies weren't fooled.
1942: After taking it on the chin since December of the previous year, the U.S. went on the offensive in the Pacific, landing units of the 1st Marine Division on the island of Guadalcanal.