An excellent student with a "particularly retentive memory and inexhaustible patience",[4] he calculated an orbit for the next appearance of Halley's Comet (in 1759), and correctly reduced Lacaille's observations of 515 stars.

Bailly gained a high literary reputation thanks to his Eulogies for King Charles V of France, Lacaille, Molière, Pierre Corneille and Gottfried Leibniz, which were issued in collected form in 1770 and 1790.

[6]: 98  Though calls on his time from his mayoral duties restricted his involvement in the group, by May 1790, Bailly had risen to presiding officer of the club.

[6]: 38  His views are depicted in the following passage of his Mémoires: "... in the executive assembly, the mayor who presides over it is a specific officer of the commune.

Bailly had deputies gather grain that was being hoarded, made the sale of wheat mandatory by farmers, and helped the bakers by making them first in line in the village markets.

To deter these attacks, Bailly signed a decree imposing a fine of five hundred livres on anyone found obstructing such convoys.

[6]: 40  Doing so led to order being established within the different jurisdictions, allowing The Communal Assembly, with the help of Bailly, to gain control of the food crisis.

The mayor not only played a role in strengthening the National Guard, but also issued orders to Lafayette when trying to maintain civility within the city.

[6]: 50  Bailly's use of troops was to secure the prisons, certify the droits d'entrée would be collected, and to ensure that beggars would not congregate in the city.

In an unsuccessful attempt at financial reconstruction, the National Assembly had taken control of church property, making it available to buyers through the issue of non-negotiable bonds known as "assignats".

[6]: 53  Bailly, along with the Municipal Bureau, then came up with a proposition on 10 March 1790, asking the government to give the city of Paris 200,000,000 livres worth of church land for it to sell to private investors in a period of three years.

After a failed attempt by the royal family to flee the country, Bailly tried to contain the growing republican crowds asking for the King to step down.

[13]: 174–190  Bailly soon heard of a gathering at the Champ de Mars, where citizens were meeting to sign petitions calling for the overthrow of the King.

In July 1793, Bailly left Nantes to join his friend Pierre-Simon Laplace at Melun, but was recognized there and arrested.

On 12 November 1793, he was guillotined at the Champ de Mars, a site selected symbolically as the location of his betrayal of the republican movement.

The little red flag he had used to give the order to fire on the crowds on the Champs de Mars was tied to the cart that took him to his death, and burned in front of him before he was executed.

[14] It was the revival of this event as a part of republican heritage after 10 August 1792, as well as a campaign of municipal persecution led by Marat, that ultimately resulted in Bailly's execution, as well as that of "many of his colleagues".