Final answer:
President Thomas Jefferson sent James Monroe to France to join Robert Livingston in negotiations that ultimately led to the Louisiana Purchase.
Step-by-step explanation:
President Thomas Jefferson sent James Monroe to France to assist Robert Livingston, the American envoy, in negotiations. Their main objective was to secure access to New Orleans, but the circumstances were favorable for a larger deal.
The failure of Napoleon's vision for Louisiana due to the successful Haitian slave revolt, along with his inability to restore the empire lost in the French and Indian War, led to Napoleon agreeing to the sale of the Louisiana territory in early 1803. This event is famously known as the Louisiana Purchase.