The goal of the expedition was to accurately determine the roundness and shape of the Earth for the purposes of improving the two countries' nautical knowledge, providing their navies an advantage over the numerically superior Royal Navy. Two expeditions were sent, one to the North Pole, led by Anders Celsius, the other to Peru.
The Peru expedition consisted of French astronomers Louis Godin, Charles Marie de La Condamine, Pierre Bouguer, and Spanish chaperones, Antonio de Ulloa and Jorge Juan y Santacilia. Secretly, Godin intended to use the expedition as a front for smuggling, and chafed at the concessions that the Spanish requested, such as only allowing a Spanish ship to access Quito. Conversely, La Condamine and Bouguer concluded that for all the Spanish military might, the French were stronger in the sciences, though they spoke highly of de Ulloa, considering him a talented prodigy.
In 1735, the scientists stayed in Saint-Domingue for six months to focus on preliminary observations. It was during this time that Adéwalé, an Assassin and supporter of the Maroon rebellion in Port-au-Prince, uncovered the existence and aims of the planned expedition. He arranged for a number of literate slaves of the rebellion's choosing to join the expedition, in the hope that any navigational secrets learned might be shared with the Assassin Brotherhood and the Maroons. The expedition was ambushed by pirates as it left Port-au-Prince, but Adéwalé's ship, the Experto Crede, repelled the attackers, enabling the voyage to continue without incident.
Though both expeditions were successful, results of the Polar Expedition ultimately overshadowed the mission to Peru.