As Secretary of State, John Quincy Adams negotiated a treaty with Great Britain for Oregon Country. Made Manifest Destiny an official United States policy. Convinced Great Britain that it could not control Florida. Negotiated a treaty with Spain for control of Florida.

D. negotiated a treaty with Spain for control of Florida.

As Secretary of State, John Quincy Adams negotiated a treaty with Spain for control of Florida.

The Treaty of Adams-Onis was the result of the negotiation between Spain and the United States to fix the border between the American nation and the then viceroyalty of New Spain.

Luis de Onis came as a representative of King Fernando VII of Spain, and Secretary of State John Quincy Adams did it by the American government. The negotiation began in 1819 and although it was signed in that same year, it was not ratified until February 22, 1821 by both parties.

Through this treaty, Spain ceded definitively Florida, Louisiana and the navigation by the Mississippi river to the United States of America.