Early in 1861, an event occurred which added force to McGee's advocacy of British-American union. In the gloom of an April morning, the guns of the confederate troops outside Fort Sumter boomed their first discharge, and the American civil war began. During the next five years a titanic struggle was waged in the republic. The issues and nature of this war might seem of little interest to the British colonists. They were sufficiently remote from the stage of conflict. Yet few events in the century so quickened and shaped development in the British communities as this. McGee was quick to see its implications. "That shot fired at Fort Sumter, on the 12th of April, 1861, had a message for the north as well as for the south.... That shot fired at Fort Sumter was the signal gun of a new epoch for North America, which told the people of Canada, more plainly than human speech can express it, to sleep no more except on their arms." The civil war made the northern states a military power, and whatever turn the struggle might take the British colonies were in danger from aggressive action. If the federal government failed to conquer the South, it might, as some politicians urged, obtain compensation by absorbing the British possessions. Even in case of victory the spirit of military aggression might so control northern statesmen as to lead to the conquest of Canada. From the beginning of the war a very active newspaper campaign had been going on against Canada, led by the New York _Herald_, a paper which represented the opinions of Seward, Secretary of State. Significantly also it had the largest circulation of any journal in the United States. It declared emphatically that Canada geographically was an annex to the Republic, and that, if an army were sent there, its inhabitants would at once declare their independence of Britain. After the _Trent_ affair of 1861, when two southern gentlemen were removed from the British steamer _Trent_ by federal sailors, these annexationist opinions found more heated expression. McGee, who kept in close touch with American opinion, became acutely aware of Canada's danger. On every available occasion, he publicly pleaded that preparation be made for defence and the most essential preparation was colonial union. The situation demonstrated Æsop's fable of the sticks. In a bundle they were unbreakable, but asunder they could be snapped with ease. He was convinced that the colonies had reached the cross-roads of their destiny. The pressure of events across their frontiers and their own political development brought them face to face with a number of alternatives, one of which must be chosen. They must either (1) strengthen themselves as members of the Empire by union amongst themselves; (2) become independent states and face the perils of such a situation; or (3) agree to be absorbed in the United States and lose their individuality as British-American communities.