Sullivan helped unify the three military services under the first secretary of defense, James V. Forrestal, and made the farsighted decision to build the USS Nautilus, the country’s first nuclear-powered submarine. A man of principle, Sullivan courageously resigned in April 1949 to publicly protest the decision of the new secretary of defense, Louis Johnson, to suddenly cancel—without consultation with the Navy—the construction of the United States, a new aircraft supercarrier, calling Johnson’s act detrimental to the nation’s future defense. At the same time he protested Johnson’s imminent decision to terminate the Marine Corps and fold it into the Army. Sullivan sacrificed his future governmental career for principles he refused to abandon, and he let the public know what was going on. He epitomized politics based on good sense, patriotism, and collegiality rather than rabid partisanship. In the decades since, his manner, foresight, and judgments have been vindicated. The United States has been safer for it.