What is the meaning for each shot for a 3 volley salute at a military funeral?
Redleg an MikeGolf have it right. But it originated in Europe long before the American Civil War. 3 shots were used to resume battle after the recovery and burial of the dead during long battles. A 21 gun salute originates in naval tradition, where a warship would fire its cannons harmlessly out to sea, until all ammunition was spent, to show that it was disarmed, signifying the lack of hostile intent. As naval customs evolved, 21 volleys came to be fired for heads of state, with the number decreasing with the rank of the recipient of the honor. Multiples of 21-gun salutes may be fired for particularly important celebrations.
