What were the Blue Moons during the Civil War years (1861-1865)?
A Blue Moon is the second full Moon in a month with two full Moons. Since the time between two full Moons (the synodic month) is 29.530588 mean solar days (29 days, 12 hours, 44 minutes, 3 seconds), this is somewhat shorter than all calendar months except February. A Blue Moon will occur on average every two or three years. During the Civil War, from April 12, 1861 to June 2, 1865, only one Blue Moon occurred and that was in July of 1863.