But she was sharply warned that such aid would not be given, and the Oregon dispute was settled in the Anglo-Saxon fashion of vigorous legal argument, followed by a fair compromise.

The Mexican war resulted in the acquisition of California by the United States.

British agents in this province of Mexico, and British admirals on the Pacific were cautioned to take no active steps in opposition.
Thus British policy, after Texan annexation, offered no barrier to American expansion, and much to British relief the fear of the extension of the American plans to Mexico and Central America was not realized.
The United States was soon plunged, as British statesmen had prophesied, into internal conflict over the question whether the newly-acquired territories should be slave or free.
The acquisition of California brought up a new problem of quick transit between Atlantic and Pacific, and a canal was planned across Central America.

Here Britain and America acted together, at first in amity, though the convention signed in 1850 later developed discord as to the British claim of a protectorate over the Atlantic end of the proposed canal at San Juan del Nicaragua.

But Britain was again at war in Europe in the middle 'fifties, and America was deep in quarrel over slavery at home.