During the next two years, she conducted exercises and provided services to surface ships and to United States Navy and United States Army air units along the West Coast and in the Hawaiian area. In the fall of 1941, Submarine Division 21 (SubDiv 21) - of which she was now a part - was transferred to the Asiatic Fleet. Departing Pearl Harbor on 24 October, she reached Manila on 10 November, and 34 days later, cleared that bay to commence her first war patrol. She headed north to intercept Japanese forces moving into northern Luzon to reinforce those already landed at Vigan and Aparri, Cagayan.