My best reply would be to quote myself from two years ago. One of my blogpost's during 2015 included the swearing of oaths to the emperor by the deputies and army, I trust you will forgive the apparent pomposity of using my own material as an initial
reply, but I wrote as follows:

"Dressed in his robes of state, Napoleon looked over the Champ de Mai in Augustan splendour. It could have been twelve years ago, in the glory days before Austerlitz. Before the field of Eylau and frozen hell of Russia or the mud and betrayal of 1814. Rank upon rank of troops in magnificent dress uniforms waited to be issued their Eagle tricolours gilded with their old battle honours. After the Archbishop of Tours had said Mass, the Emperor arose from his throne and made a speech, after which he placed his hand on the New Testament and made an oath to observe the Constitution of the Empire and ensure it was respected. Then the Deputies and Dignitaries repeated it with a codicil of loyalty to the Emperor after which the assembly solemnly affirmed “We swear it”. The Eagles were presented and the troops swore to recognise them as their rallying signs, to die protecting them and to never abandon them. Amidst the cries of Vive l’Empereur and Vive L’Armée, it all seemed to have happened so fast. It was the 1st of June 1815"

The scene was painted by Heim.

I cited the following sources & the article in question of which this was a prelude was principally about Napoleon's return to power.
Waterloo new perspectives: David Hamilton Williams.
Waterloo 1815 (vol 2) Ligny: John Franklin.
Waterloo, Napoleon’s Last Campaign: Christopher Hibbert.
The Waterloo Companion: Mark Adkin.
A narrative of the political and military events of 1815: James M’Queen.
L’Armée Français: Jules Richard & Edouard Detaille.
The Campaign of 1815: Siborne.