Perhaps the most important contribution made by Canada to the development of armed conflict law, and one that is possibly equal in significance to that made by any other country, was not in fact made by Canada as such, but rather in response to Canadian actions. During the 1837 rebellion, Canadian forces had seized an American vessel, The Caroline, which had been used to support the rebels, and tipped it over Niagara Falls. In response to United States protests, the Canadian authorities justified their action on the ground of self-defence. In negotiations with the British, who then governed Canada, Daniel Webster, United States Secretary of State, propounded a formulation of the plea of self-defence which has stood the test of time. In his words, preventive action in foreign territory is only justified in the case of “an instant and overwhelming necessity for self-defence, leaving no choice of means, and no moment of deliberation.” This concept of the right is so universally accepted today that it was adopted in its Judgment by the International Military Tribunal at Nuremberg when rejecting Germany’s explanations of the invasions of Denmark and Norway.