[114] The same year, he sent Henry Wheaton as a minister to Berlin, where he negotiated and signed a trade agreement with the Zollverein, a coalition of German states that managed tariffs. This treaty was rejected by the Whigs, mainly as a show of hostility toward the Tyler administration. Tyler advocated an increase in military strength and this drew praise from naval leaders, who saw a marked increase in warships.[115]
In an 1842 special message to Congress, Tyler also applied the Monroe Doctrine to Hawaii (dubbed the "Tyler Doctrine"),[116] told Britain not to interfere there, and began a process that led to the eventual annexation of Hawaii by the United States.[117]

Webster-Ashburton treaty
Secretary of StateDaniel Webster
A foreign crisis erupted in an offshoot of the Aroostook War, that ended in 1839. Citizens of Maine clashed with citizens of New Brunswick over disputed territory, that covered 12,000 square miles. In 1841, an American ship, the Creole, was transporting slaves from Virginia to New Orleans. A mutiny took place, and the ship was captured by the British and taken to the Bahamas. The British refused to return the slaves to their masters. 