Of all the events, however, that startled the British provinces out of the self-absorbed contemplation of their own little affairs, the Civil War in the United States exerted the most immediate influence. It not only brought close the menace of a war between Great Britain and the Republic, with Canada as the battle-ground, but it forced a complete readjustment of our commercial relations. Not less important, the attitude of the Imperial government toward Confederation underwent a change. It was D'Arcy McGee who perceived, at the very outset, the probable {25} bearing of the Civil War upon the future of Canada. 'I said in the House during the session of 1861,' he subsequently declared, 'that the first gun fired at Fort Sumter had a message for us.' The situation became plainer when the _Trent_ Affair embroiled Great Britain directly with the North, and the safety of Canada appeared to be threatened. While Lincoln was anxiously pondering the British demand that the Confederate agents, Mason and Slidell, removed by an American warship from the British steamer the _Trent_, should be given up, and Lord Lyons was labouring to preserve peace, the fate of Canada hung in the balance. The agents were released, but there followed ten years of unfriendly relations between Great Britain and the United States. There were murmurs that when the South was subdued the trained armies of the North would be turned against the British provinces. The termination of the Reciprocity Treaty, which provided for a large measure of free trade between the two countries, was seen to be reasonably sure. The treaty had existed through a period which favoured a large increase in the exports of the provinces. The Crimean War at first and the Civil War later had created an unparalleled demand for the food products {26} which Canada could supply; and although the records showed the enhanced trade to be mutually profitable, with a balance rather in favour of the United States, the anti-British feeling in the Republic was directed against the treaty. Thus military defence and the necessity of finding new markets became two pressing problems for Canada. From the Imperial authorities there came now at last distinct encouragement. Hitherto they had hung back. The era of economic dogma in regard to free trade, to some minds more authoritative than Holy Writ, was at its height. Even Cobden was censured because, in the French treaty of 1861, he had departed from the free trade theory. The doctrine of _laissez-faire_, carried to extremes, meant that the colonies should be allowed to cut adrift. But the practical English mind saw the sense and statesmanship of a British American union, and the tone of the colonial secretary changed. In July 1862 the Duke of Newcastle, who then held that office and who did not share the indifference of so many of his predecessors[3] to the colonial connection, wrote sympathetically to Lord Mulgrave, the governor of Nova Scotia: {27}