How did the tradition of putting a flag at half mast in mourning/respect originate?

Question

How did the tradition of putting a flag at half mast in mourning/respect originate?

Answer 1

It was considered that the space above the visible flag was occupied

by "Death's invisible flag."

Answer 2

My guess is that some time in the dim, dark past a dieing hero only hoisted his flag half way up the standard before 'checking out'.

Answer 3

When, where and why did the origin of placing the flag at half-mast come from?

It was first recorded instance July 1612, in what is now Canada.

Not definitely known why though.

Half-masting a flag is probably the last symbolic gesture of what was once in some cultures a common way of showing grief.

Some suggest that the part lowering of a flag indicates the passing of the authority represented by the flag, or that it is to leave space for 'the invisible flag of death' to be flown above the lowered flag, but these are modern attempts to explain a practice which has much older origins.

The reference to 1612 "on the occasion of the murder of James Hall by Eskimos during the first expedition in search of the North-West Passage, in which Baffin took part, when the 'Heart's Ease' rejoined the 'Patience' with "her flag hanging down and her ensign hanging over the p**p, which was a sign of death". On entering the Thames two months later the 'Heart's Ease' again lowered her flag and ensign "in token and in sign of the death of Mr. Hall", so that it was at that date well understood to signify the death of the commanding officer of a ship." from "British Flags"

It was the habit, after the restoration of the Monarchy in 1660, for ships of the Royal Navy to fly their flags at half-mast on the anniversary of the execution of King Charles I on 30th January 1649, and it is from this custom that, so far as we can trace, the present practice of announcing a death by the flying of a flag at half-mast has evolved. The earlier practice at sea was to fly a black flag or to set a black sail.

See site below for the FULL indepth history of flag half mast flying.