Geir Lundestad proposed the view that the United States became an “Empire by Invitation.” According to Lundestad, the U.S. only became an empire through its involvement in the defense of Western Europe in the early days of the Cold War. This article argues that the U.S. had already been invited to share “Empire” in the era of World War I through the “personal” relationship of two policymakers at opposite sides of the Atlantic Ocean. Indeed it might be said that the uniqueness of the Anglo-American relationship was forged by these two men. This article examines this uniqueness by analyzing the relationship between Edward Mandell House, a close friend of then-U.S. President Woodrow Wilson, and Sir Edward Grey, the British Foreign Minister when U.S. participation in World War I was a “hot-button issue.” House had earned the trust of Woodrow Wilson during the 1912 presidential election and subsequently acted as political advisor to Wilson. House and Grey laid the foundation of their solid relationship during the Mexican revolution (i.e., beginning in 1910). At the outbreak of World War I, House visited Britain to meet with Prime Minister Herbert Henry Asquith. On 17 February 1916, House and Grey produced a memorandum that stipulated that U.S. participation in World War I would be on the British side. When House returned to the U.S. at the end of his mission, Wilson was surprised at what he read and therefore amended the crucial sentence in the memorandum by adding the word “probably.” Wilson’s minor revision to the memorandum caused U.S. participation in World War I on the side of Britain to be significantly delayed. Nevertheless, the memorandum did signal the forging of a special relationship between Britain and the United States because it stipulated that, in World War I, the United States would stand on the side of Britain. Because Grey wanted to secure the imminent support of the U.S., he sought out U.S. Representatives who felt a sense of kinship with Britain. House, by contrast, pushed the idea of achieving world peace via the support of Anglo-American cooperation. Yet even before the end of World War I, following the defeat of the Axis powers, House began to imagine a new world order. He thus organized a project he named “The Inquiry.” For this project, which was conducted during the winter of 1917-1918, brilliant young scholars researched a vision of a post-World War I world. The first epoch in which the U.S. became a world power was not during the early days of Cold War, as scholars such as Geir Lundestad contend. Rather, the U.S. was already involved in Empire building through its participation in World War I and the close “personal” relationship forged between Edward Mandell House, a close friend of then U.S. President Woodrow Wilson, and Sir Edward Grey, the British Foreign Minister at the time. The personal relationship of these two men opened an Anglo-American intellectual world-visionary communication interface and led to the establishment of major think tanks, both in Britain and the United States, that focused on international relations on both sides of the Atlantic Ocean.