gain a foothold for future operations. Blue had nine battleships, one aircraft carrier, and many lesser ships. Black defended with one modern aircraft carrier and some fictional battleships, as well as a number of actual cruisers, submarines, and many other ships. Blue's advance was quickly located by Black's picket line of submarines which then took heavy losses from air attack. Both sides put a priority on destroying the enemy aircraft carrier, launching air attacks almost simultaneously after a few days of probing. Significant damage was laid on both carriers, with Blue's carrier eventually "sunk" by torpedo from a Black destroyer. After-action critiques stressed the growing importance of naval aviation, and an increased need for the construction of aircraft carriers in the event of a war in the Pacific. Submarines operating at or near the surface were seen to be critically vulnerable to air observation and attack. The exercise showed that one carrier was insufficient for either fleet attack or area defense, so the practice of two or more carriers operating together became policy. Admiral Harry E. Yarnell said that six to eight carriers would be required for a Pacific campaign, but no orders were placed for new carriers, as Depression-era financial difficulties caused President Herbert Hoover to limit naval expenses. Fleet Problem XIV Held 10–17 February 1933, Fleet Problem XIV was the first naval exercise to test simulated aircraft carrier attacks against the west coast of the United States. Pacific cities had for decades vied for permanent stationing of U.S. military assets, and vulnerabilities exposed through the exercises were used by metropolitan navy boosters to leverage their cases. In spite of early Navy plans for San Francisco to be home port for the main west coast fleet, these plans had failed to materialize with San Diego incrementally gaining the majority of navy investments. Fleet Problem XIV occurred the month before Franklin D. Roosevelt, a former Assistant Secretary of the Navy, took the office of the presidency. The results of the exercise between the U.S. Navy's Black and Blue fleets, were mixed. The simulated attacks had certainly been mitigated by the defensive Blue fleet, however the Black fleet had scored key victories with strikes on San Pedro and San Francisco, California. Fleet Problem XV Held in May 1934 in Hawaii, this was a three-phase exercise which encompassed an attack upon and defense of the Panama Canal, the capture of advanced bases,