southern California coast before getting underway on 26 September for Hawaii. Reaching Pearl Harbor on 2 October, Aylwin underwent repairs and alterations there through November. She arrived back at San Diego on 12 December and conducted training exercises off the South Coronados Island of Mexico before ending the year 1938 berthed in a destroyer nest in San Diego harbor. 1939 Four days into 1939, Aylwin got underway for Panama and reached Balboa on 13 January. After transiting the Panama Canal the next day, she operated out of Gonaïves, Haiti; Guantánamo Bay, Cuba; and, Port-au-Prince, Haiti, before getting underway on the 13th for her initial station during Fleet Problem XX. These exercises took place in the Caribbean and arrayed the Battle Force against the Scouting Force. After fueling from on 17 February, Aylwin operated with and which acted as a raiding force during one phase of the problem. Ultimately, the "battle" reached its conclusion, the fleet battle. The forces then all retired to Culebra Bay, Puerto Rico, where President Franklin D. Roosevelt reviewed them from the deck of Houston on the last day of February. After visiting Cienfuegos and Guantánamo Bay, Cuba, Aylwin operated briefly out of Gonaïves before returning to Guantanamo on 31 March. She got underway on 8 April for Yorktown, Virginia, and, en route north, acted as plane guard for Lexington. Aylwin reached Yorktown on 12 April, but the Fleet's visit to that area was soon cut short by orders to return to the Pacific. Underway at 04:04 on 20 April, Aylwin took station with the rest of her division around the carriers. She planeguarded for en route to Panama; transited the Canal on 29 April; and, after tarrying briefly at Balboa, got underway for San Diego on 2 May. Reaching her home port on the 12th, the destroyer operated off southern California before entering the Mare Island Navy Yard on 18 June for repairs and alterations lasting until 8 October. She got underway on the morning of 11 October, bound once more for Hawaii. The Navy formed a "Hawaiian Detachment" under Vice Admiral Adolphus Andrews and based it at Pearl Harbor—a step foreshadowing the basing of the entire Fleet there the following spring. Aylwin arrived at Pearl Harbor on 18 October 1939 and, over the next few months, alternated periods in port at "Pearl" with varied exercises in the Hawaiian operating area. 1940 In the spring of