1920 Summer Olympic Opening Ceremony - Antwerp

The Games of the VII OlympiadAntwerp, Belgium
1920

The Olympic Flag is flown for the first time at the 1920 Antwerp Games

Olympic Ceremony Records
italics indicate records at the time

First Athlete's Oath
First Release of Doves
First Use of the Olympic Flag
First Airplane Flyover
Worst Attended Official Opening Ceremony (20,000 - 1904 St. Louis was smaller but it was not an official opening ceremony.)
Smallest Stadium to Host an Official Opening Ceremony (12,771 - 1904 St. Louis was smaller but it was not an official opening ceremony)
Most Nations Participating (29) - previous Stockholm 1912 (28)
Most Athletes Participating (2,626) - previous Stockholm 1912 (2,406)
Most Olympic Events (154) - previous London 1908 (110)

Opening CeremonyOlympisch Stadion (12,771)
August 14, 1920
Many websites (wikipedia, official olympic sites) mistake the first competition of the games (April 1920) with the Opening Ceremony (August 14, 1920). If you can read French, you will see in the official document below that the ceremony was held on August 14.
Video
Official Report
Opening Ceremony HighlightsThe Opening Ceremony of the 1920 Olympics in Antwerp were subtle compared to the mass displays of the 1912 games in Stockholm. This ceremony however has been one of the most influential ceremonies in all of Olympic history. The first raising of the Olympic Flag, the first Athlete's Oath, and the first release of Doves as a symbol of peace. Antwerp and Belgium as a whole lost many people during WWI. The games were awarded to Antwerp to commemorate those lost in the war. These ceremonies were much more somber and filled with ceremonial displays. Here is the brief summary of the Opening Ceremony.

Church service: De Profundis chanted at the Cathedral to commemorate athletes who died in the war and a Te Deum chanted to commemorate the victorious allied countries
King and Queen of Belgium parade to the Olympic Stadium - many follow on foot.
The Parade of Nations
Airplane Flyover
The King of Belgium is introduced and declares the games open.
Trumpet fanfare is sounded as the Olympic Flag is hoisted for the first time. (fanfare is unknown)
Doves are released for the first time, as a symbol of peace.
Athlete's Oath taken for the first time
The Opening Ceremony concluded

Among other cultural festivals, Antwerp and many other Belgian towns celebrate an Ommegang. These originated as church processionals going through the streets of the city, but now are medieval parades and festivals. Below are two photos from the Antwerp Ommegang on the 9th of August, 1920 celebrating the Olympic Games.