<P> Outright war was a possibility in late 1861, when the U.S. Navy took control of a British mail ship and seized two Confederate diplomats . Confederate President Jefferson Davis had named James M. Mason and John Slidell as commissioners to represent Confederate interests in England and France . They went to Havana, in Spanish Cuba, where they took passage for England on the British mail steamer Trent . The American warship USS San Jacinto under Captain Charles Wilkes was looking for them . It was generally then agreed that a nation at war had the right to stop and search a neutral merchant ship if it suspected that ship of carrying the enemy's dispatches . Mason and Slidell, Wilkes reasoned, were in effect Confederate dispatches and so he had the right to remove them . On November 8, 1861, he fired twice across the bow of the Trent, sent a boat's crew aboard, seized the Confederate commissioners, and bore them off in triumph to the US, where they were held prisoner in Boston . Wilkes was hailed as a national hero . </P> <P> The violation of British neutral rights triggered an uproar in Britain . Britain sent 11,000 troops to Canada, the British fleet was put on a war footing, with plans to capture New York City if war broke out, and a sharp note was dispatched to Washington to demand return of the prisoners and an apology . Lincoln, concerned about Britain entering the war, ignored anti-British sentiment and issued what the British interpreted as an apology, without apologizing, and ordered the prisoners to be released . </P> <P> War was unlikely in any event, as the United States was providing Britain with over 40% of its wheat ("corn") imports during the war years, and suspension would have caused severe disruption to its food supply . Britain imported about 25 - 30% of its grain, and poor crops in 1861 and 1862 in France made Britain even more dependent on shiploads from New York City . Furthermore, British banks and financial institutions in the City of London had financed many projects such as railways in the US . There were fears that war would result in enormous financial losses as investments were lost and loans defaulted on . </P> <P> Britain's shortage of cotton was partially made up by imports from India and Egypt by 1863 . The Trent Affair led to the Lyons - Seward Treaty of 1862, an agreement to clamp down hard on the Atlantic slave trade by using the US Navy and the Royal Navy . </P>

Who helped the north during the civil war