The origin of gun salutes is usually attributed to soldiers or
other armed types demonstrated peaceful intentions by placing
their weapons in a position that rendered them ineffective. As
cannons and small arms came into use, a good way to render them
ineffective and demonstrating peaceful intentions, was to fire
them, as reloading was a real pain. At sea, seven shots became
the norm, probably because of superstition and mysticism about
the number seven. On land, with a less limited supply of
gunpowder, they could fire three guns for every one shot from a
ship, so a salute from a ship of seven guns would be answered by
a salute from the shore batteries of 21 guns. When gunpowder
technology and storage improved, ships at sea adopted the salute
of 21 guns.
There is a complex
protocol for salutes. Twenty one guns are only used to salute a
national flag, the sovereign or chief of state of a foreign
nation, a member of a reigning royal family, and anyone who has
ever been elected President of the US. A vice-president, speaker
of the house, American or foreign ambassador, a premier or prime
minister (unless sovereign), chief justice, cabinet member,
state governor, secretary or ranking general of a branch of the
armed forces, and president pro tem of the senate all receive 19
gun salutes on entering. Generals, admirals, the assistant
secretary of defense, and chairpersons of House committees
receive 17. There are 15, 13, and 11 gun salutes for people of
descending rank, both military and civilian.
For a full-honor
funeral at Arlington, a President gets 21 guns. A secretary of
defense, chairman of the Joint Chiefs of Staff, or other
military officer given command over multiple branches of the
service receives 19. Seventeen guns are fired for a four-star
general, 15 for a three-star, 13 for a two-star, and 11 for a
one-star.