The 1916 Naval Expansion Act represented the culmination of 20 years of planning by the U.S. Navy's professional officers corps to build a fleet of top-rank status. The Navy's program relied on the tenets of Alfred Thayer Mahan, which dictated that a large battle fleet was required to counter one or more potential adversaries. A consistent expansion program had been regularly rejected prior to 1916. The outbreak of the First World War provided impetus to expand the Navy, though President Woodrow Wilson and Secretary of the Navy Josephus Daniels resisted. Opponents of greater preparedness rarely spoke about the size of the Navy. Their opposition to war and armaments spoke for those who opposed militarism of any kind. The intellectual division in Congress reflected the range of opinion on both sides. Wilson shifted to preparedness after Germany's unprecedented submarine campaign killed U.S. citizens at sea. But Wilson was not clear on exactly what the country was preparing for. The Navy's proposed program reflected its long-held battle fleet-centered policies and failed to adequately account for lessons naval officers should have been learning about the war being fought. Daniels' failure to allow greater preparedness measures prior to 1915 or grasp the importance of professional officers' assessments exacerbated the problem. This contributed to a missed opportunity for Congress to focus on what the Navy might need if the country was drawn into war. Upon entering the war, the Navy discovered how unprepared it was and immediately altered the 1916 program, concentrating on building destroyers to combat the submarine threat. After the war, the Navy was eager to resume fleet expansion, but Congress pursued the kind of international disarmament effort that was included in the 1916 legislation as a means of obtaining the support of those opposed to a large Navy. The steel and shipbuilding businesses were critical to securing the Navy's expansion and pointing the way to the kinds of government-business partnerships that served effectively in the Second World War. Conflicts over the costs and production of armor plate highlighted the tempestuous nature of the Navy-business relationship and the intersection with congressional politics.