In 1778 the expedition under d'Estaing, who sent the Chasseurs-Volontaires de Saint-Domingue to assist the U.S. Continental Army, Chavannes was one of those who had volunteered.

[1] When Vincent Ogé landed near Cap-Français, 23 October 1790, intending to create an agitation amongst the people of African descent in favor of their political rights, Chavannes sided with him.

Chavannes wanted all the slaves to be declared free, but Ogé did not follow his advice, and informed the assembly of his intention to take the opposite course.

[1] The mulattoes being defeated by the colonists, Ogé, Chavannes, and a few others took refuge in the Spanish part of the island, and the Saint Dominican assembly asked for their extradition, according to treaty.

The jurist Vicente Faura made a powerful plea in their favor, and the king of Spain gave him a decoration, but the Royal Audiencia of Santo Domingo decided against the refugees, who were delivered to the Saint Dominican authorities on 21 December 1790.