von Mantey wrote in his diary that the "East Coast is the heart of the United States and this is where she is most vulnerable. New York will panic at the prospect of bombardment. By hitting her here we can force America to negotiate." Büchsel carefully noted that a condition for success in the German invasion of America was the absence of a major conflict in Europe. Another condition was a poor state of American preparedness. Both of these conditions were eroding at the time of Büchsel's authorship of the third plan. The US had been aroused, filled with a new martial spirit after its victory over Spain in 1898. America had immediately begun building battleships, and the balance of sea power was shifting away from the German advantage reported by von Diederichs. The British Royal Navy, the strongest navy in the world, was expanding further, and other countries were planning very heavy dreadnought-type battleships. This put extra pressure on the German Navy which never reached a position of parity in the Anglo-German naval arms race nor did it expand enough to satisfy the warship and troopship numbers specified by von Mantey and then by Büchsel in the various US invasion plans. The Venezuela Crisis of 1902–1903 showed the world that the US was willing to use its naval strength to force an American viewpoint in world politics; the crisis established President Theodore Roosevelt's Roosevelt Corollary to the Monroe Doctrine, setting a precedent for US intervention in South American–European affairs. In April 1904, the balance of power was seriously shifted in Europe with the signing of the Entente Cordiale by Britain and France. This improved diplomatic relationship between the two countries allowed French and British military forces to be shifted elsewhere, usually to the detriment of Wilhelm II's hope for a Kolonialreich—an empire of German influence much like the British Empire and the French colonial empire. Tsar Nicholas II of Russia refused to form a military alliance with Germany so the Kaiser determined that he should focus on strengthening Germany for a possible European conflict rather than an overseas invasion. The US invasion plans were shelved in 1906. Discovery Hints of the German war plans were first found by scholar Alfred Vagts, who while doing research in the German Foreign Office on Wilhelmstrasse in Berlin during the 1930s, saw copies of reports from 1900 from Rebeur-Paschwitz to Tirpitz. These discussed