Which 1958 military ceremony was part of the first federally organized Dominion Day celebration?

Trooping the Colour was the military ceremony included in the first federally organized Dominion Day celebration in 1958.

Before 1958, July 1 celebrations were generally organized locally, and Dominion Day had not consistently been a major national event. Prime Minister John Diefenbaker asked Secretary of State Ellen Fairclough to coordinate a federal celebration, giving the effort a national structure and a budget of $14,000. Federal leaders also attended, despite Parliament traditionally sitting on July 1.

The official program usually featured Trooping the Colour on Parliament Hill in the afternoon and evening, followed by a mass band concert and fireworks. Trooping the Colour is a ceremonial military parade involving the presentation and escort of a regiment’s colour, or flag. It is distinct from the Beating Retreat, which traditionally marks the end of a military day, and from the Changing of the Guard, a sentry-relief ceremony. Later celebrations added concerts and cultural performances, helping Dominion Day become more broadly popular.