The first intimation of the new American policy came in relation to the State of Texas which had revolted from Mexico in 1836, and whose independence had been generally recognized by 1842.

To this new state Britain sent diplomatic and consular agents and these reported two factions among the people--one seeking admission to the American Union, one desiring the maintenance of independence.
In 1841 Aberdeen had sent Lord Ashburton to America with instructions to secure, if possible, a settlement of all matters in dispute.

Here was a genuine British effort to escape from national irritations.

But before the Treaty of 1842 was signed, even while it was in the earlier stages of negotiation, the British Government saw, with alarm, quite new questions arising, preventing, to its view, that harmonious relation with the United States the desire for which had led to the Ashburton mission.

This new development was the appearance of an American fever for territorial expansion, turning first toward Texas, but soon voiced as a "manifest destiny" which should carry American power and institutions to the Pacific and even into Central America.