Throughout the early years of the war, British foreign secretary Lord John Russell, Emperor Napoleon III of France, and, to a lesser extent, British Prime Minister Lord Palmerston, showed interest in recognition of the Confederacy or at least mediation of the war. William Ewart Gladstone, the British Chancellor of the Exchequer (finance minister, in office 1859–1866), whose family wealth was based on slavery, was the key Minister calling for intervention to help the Confederacy achieve independence. He failed to convince prime minister Palmerston. By September 1862 the Union victory at the Battle of Antietam, Lincoln's preliminary Emancipation Proclamation and abolitionist opposition in Britain put an end to these possibilities. The cost to Britain of a war with the U.S. would have been high: the immediate loss of American grain-shipments, the end of British exports to the U.S., and the seizure of billions of pounds invested in American securities. War would have meant higher taxes in Britain, another invasion of Canada, and full-scale worldwide attacks on the British merchant fleet. Outright recognition would have meant certain war with the United States; in mid-1862 fears of race war (as had transpired in the Haitian Revolution of 1791–1804) led to the British considering intervention for humanitarian reasons. Lincoln's Emancipation Proclamation did not lead to interracial violence, let alone a bloodbath, but it did give the friends of the Union strong talking points in the arguments that raged across Britain.