Por que o soldado deslizou 3 cartuchos na bandeira dobrada?

Esta é uma parte comum de um funeral miltário

A standard part of any military funeral is the ceremonial shooting of three volleys in honor of the deceased. The three spent shell casings are presented to his or her next of kin.

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MAS NÃO é uma 21ª saudação de arma , isso é um equívoco comum . É uma saudação de 3 vôos (Wikipedia) e pode consistir de 3, 5 ou 7 firers

Not a 21-Gun Salute

This funeral salute often is mistaken by people who aren't involved in the military as a 21-gun salute, although it is entirely different. The three volleys in the funeral salute are fired from rifles, not "guns."

In the military, a "gun" is actually a large-caliber weapon, such as a cannon. The 21-gun salute stems from naval tradition, and it is used to mark certain anniversaries, salute heads of state, and reigning royalty and honor national flags.

Battlefield Custom of Three Volleys

The tradition dates back to the European dynastic wars, which were between 1688 and 1748. The volleys were shots fired on the field during a battle, signaling a pause in the fighting. It was intended to allow time for both sides to remove the bodies of their fallen soldiers from the battlefield.

Service Members Needed for Three Volleys

The firing team in this ceremony can consist of any number of service members, but one usually sees a team of eight, with a non-commissioned officer (NCO) in charge of the firing detail. Whether the team consists of three, eight, or 10 service members, each member fires three times.

Three Bullet Casings Slipped Into Folded Flag

The military funeral honors also include a ceremony in which the honor guard removes the flag from the casket and carefully folds it, with the blue field of stars facing up. Then, the folded flag is presented to the deceased person's family as a token of gratitude for that person's service.

The flag detail often slips three shell casings into the folded flag before presenting the flag to the family. Each casing represents one volley. This gesture provides a slightly different meaning for the symbolism of the three bullets in a military funeral.

Um soldado que é enterrado com honras recebe uma saudação de 21 armas. Hoje, isso seria composto de sete soldados que disparavam suas armas 3 vezes. (7x3) Então os 3 cartuchos seriam daquele contexto.