The Champ de Mai ([ʃɑ̃ də mɛ]; "Field of May") was a public assembly held by Napoleon on the Champ de Mars, Paris, a large open area near the École militaire, on 1 June 1815. This was during the Hundred Days, the period between Napoleon's return from exile and the restoration of the Bourbon kings following his failed Waterloo campaign. The objective of the Champ de Mai was to gather public support behind Napoleon's Charter of 1815, a constitutional reform that promised a more liberal government than under his earlier rule. The Charter was put to the citizens in a constitutional referendum and the results of this would be announced during the ceremony by representatives of the electoral college.
Several temporary structures were constructed including a semi-amphitheatre, housing 9–10,000 military and civic dignitaries; a throne platform for Napoleon and his brothers; and a religious altar and a platform from which Napoleon was to distribute imperial eagles, the French standards, to his troops. Around 200,000 spectators attended the event which included a parade of 25,000 soldiers and 25,000 National Guardsmen.
After a Catholic mass, the results of the referendum, a landslide in favour, were announced. Napoleon afterwards signed the Charter and swore, on a copy of the New Testament, that he would uphold it. The distribution of standards overran and those of the National Guard had to be distributed at the Louvre three days later.