The acute stage of controversy over West Indian trade was not reached until some thirty years after American Independence, but the uncertainty of such trade during a long period in which a portion of it consisted in unauthorized and unregulated exchange was a constant irritant to all parties concerned.  Meanwhile there came the War of 1812 with its preliminary check upon direct trade to and from Great Britain, and its final total prohibition of intercourse during the war itself.  In 1800 the bulk of American importation of manufactures still came from Great Britain.  In the contest over neutral rights and theories, Jefferson attempted to bring pressure on the belligerents, and especially on England, by restriction of imports.  First came a non-importation Act, 1806, followed by an embargo on exports, 1807, but these were so unpopular in the commercial states of New England that they were withdrawn in 1810, yet for a short time only, for Napoleon tricked the United States into believing that France had yielded to American contentions on neutral rights, and in 1811 non-intercourse was proclaimed again with England alone.  On June 18, 1812, America finally declared war and trade stopped save in a few New England ports where rebellious citizens continued to sell provisions to a blockading British naval squadron.

For eight years after 1806, then, trade with Great Britain had steadily decreased, finally almost to extinction during the war.  But America required certain articles customarily imported and necessity now forced her to develop her own manufactures.  New England had been the centre of American foreign commerce, but now there began a trend toward manufacturing enterprise.  Even in 1814, however, at the end of the war, it was still thought in the United States that under normal conditions manufactured goods would again be imported and the general cry of “protection for home industries” was as yet unvoiced.  Nevertheless, a group of infant industries had in fact been started and clamoured for defence now that peace was restored.  This situation was not unnoticed in Great Britain where merchants, piling up goods in anticipation of peace on the continent of Europe and a restored market, suddenly discovered that the poverty of Europe denied them that market.  Looking with apprehension toward the new industries of America, British merchants, following the advice of Lord Brougham in a parliamentary speech, dumped great quantities of their surplus goods on the American market, selling them far below cost, or even on extravagant credit terms.  One object was to smash the budding American manufactures.