Based on the information in the excerpt, the most appropriate inference is: The attacks on American shipping vessels led to a build-up of an American naval force.
The excerpt discusses how American shipping was initially defenseless against French privateers, but by 1800, the United States began to strengthen its naval presence by arming merchantmen and deploying U.S. warships to protect the sea-lanes. This indicates a direct response to the challenges posed by the ongoing conflict between France and England.