Fortunately for the New Navy, its most ardent political supporter, Theodore Roosevelt, became President in 1901. Under his administration, the Navy went from the sixth largest in the world to second only to the Royal Navy.[87] Theodore Roosevelt's administration became involved in the politics of the Caribbean and Central America, with interventions in 1901, 1902, 1903, and 1906. At a speech in 1901, Roosevelt said, "Speak softly and carry a big stick, you will go far", which was a cornerstone of diplomacy during his presidency.[88]
Roosevelt believed that a U.S.-controlled canal across Central America was a vital strategic interest to the U.S. Navy, because it would significantly shorten travel times for ships between the two coasts. Roosevelt was able to reverse a decision in favor of a Nicaraguan Canal and instead moved to purchase the failed French effort across the Isthmus of Panama. The isthmus was controlled by Colombia, and in early 1903, the Hay–Herrán Treaty was signed by both nations to give control of the canal to the United States. After the Colombian Senate failed to ratify the treaty, Roosevelt implied to Panamanian rebels that if they revolted, the US Navy would assist their cause for independence. Panama proceeded to proclaim its independence on 3 November 1903, and USS Nashville impeded any interference from Colombia. The victorious Panamanians allowed the United States control of the Panama Canal Zone on 23 February 1904, for US$10 million.[89] The naval base at Guantanamo Bay, Cuba was built in 1905 to protect the canal.[90]
The latest technological innovation of the time, submarines, were developed in the state of New Jersey by an Irish-American inventor, John Philip Holland. His submarine, USS Holland was officially commissioned into U.S. Navy service in the fall of 1900.[91] The Russo-Japanese War of 1905 and the launching of HMS Dreadnought in the following year lent impetus to the construction program. At the end of 1907 Roosevelt had sixteen new battleships to make up his "Great White Fleet", which he sent on a cruise around the world. While nominally peaceful, and a valuable training exercise for the rapidly expanding Navy, it was also useful politically as a demonstration of United States power and capabilities; at every port, the politicians and naval officers of both potential allies and enemies were welcomed on board and given tours. The cruise had the desired effect, and American power was subsequently taken more seriously.[91][92]
The voyage taught the Navy more fueling stations were needed around the world, and the strategic potential of the Panama Canal, which was completed in 1914. The Great White Fleet required almost 50 coaling ships, and during the cruise most of the fleet's coal was purchased from the British, who could deny access to fuel during a military crisis as they did with Russia during the Russo-Japanese War.[93]