А когда, где впервые и кто придумал выносить государственные флаги стран участниц на стадион во время Олимпиад?

Кратко: Впервые на 4 олимпийских играх в лондоне, 1908 года. Думаю, что и придумал король английский Эдвард VII, которому и ему салютовали флагами все, кроме штатов.

Называется шествие Parade of Nations.

Для ответа ниже:
В 1920 году впервые показали флаг олимпиады. . который с кольцами
http://olympic-museum.de/various/flag.htm

The Parade of Flags was introduced at the IVth Olympic Games, London 1908, and King Edward VII himself was the Head of State to whom all flags were dipped in salute as the athletes marched in. That is, all flags except the flag of the USA. To the fury of King Edward, the USA shot-putter Ralph Rose refused to pay him respect by dipping the Stars & Stripes.

One reason given for this is that the flag of the United States is lowered for no mortal man. And after all, a king is merely a mortal! And that to this day, the Stars & Stripes is the only flag that is not dipped when the Head of State is saluted during the Parade of Flags. However, poetic as this explanation may be, it's not clear whether such a rule for the USA flag existed in 1908. The rule is part of the first USA Flag Code, but that Flag Code wasn't drawn up until 1923. On the other hand, in the early 20th century, veterans of the Union Army in the American Civil War waged a campaign against what they considered indignities to the Stars & Stripes, and the rule against dipping the American flag may have originated from that campaign.

Another possible explanation lies in the fact that the London organization, when decorating the stadium, forgot to display the flags of Sweden and the United States. The Swedish team in turn did not take part in the Parade of Flags; the USA team did take part in the parade, but they got even and made sure their flag was clearly visible this time: They refused to dip it in salute to the king.

The truth, as happens so often, may be a combination of both. However, quite surprisingly, on a photograph taken in London when the parade of flags had finished, all teams can be seen greeting the royal family with their flags. Even though the photograph is in black & white the dipped American flag can be made out quite clearly. Of course, this does not tell us what happened in the course of the parade, but it does show that during London 1908 there was at least one occasion where the flag bearer did indeed dip the Stars & Stripes.

Привет Ваня! ..Придумали держать и выносить флаг в Антверпене на Олипиаде 1920 года. . можно добавить когда судья берет клятву судить честно и также держит флаг. . это уже с 1972 года Мюнхенская. .
Но шагают страны с флаги в невразброс. . первой идет Греция! (искл. В 2004) а последние страна-хозяйка

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