[1] In May 1927, the S-boat moved northwest to Mare Island for overhaul, then began operations out of San Diego, California.

[1] They participated in Fleet Problem XVII en route and arrived at Coco Solo, their new home port, on 22 May.

[1] By 1 February 1942, she had conducted two defensive patrols, during which her crew became even better acquainted with the defects in the torpedoes she carried and with the limited wartime capabilities of boats of her class.

[1] Then, as the Japanese thrust toward Australia continued, the Panama S-boats prepared to assist in defensive efforts in the southwestern Pacific.

[1] On 19 June, she returned to Brisbane, where an overhaul brought the installation of temporary air conditioning and corrected some of the defects in the engines, the radio transmitter, and the bow planes which had hampered her during her recent patrol.

[1] Numerous targets were sighted; but, due to frequent squalls and her own limitations, she was unable to press home an attack.

[1] Arriving at the latter on 6 January 1943, she underwent voyage repairs, then received orders to Saint Thomas, United States Virgin Islands, for training duty.

[1] On arrival, she was ordered back to Coco Solo, whence she continued on to San Diego and a three-month tour with the West Coast Sound School.

[1] Training and minor repairs occupied the remainder of the month; and, on 31 December, she departed the eastern Aleutians for Attu.

[1] From mid-July to the end of the year, she conducted training exercises from Manus in the Admiralty Islands; then moved to Brisbane for repairs preparatory to returning to California.

[1] S-45 arrived back at San Diego in early April 1945 and resumed operations for the West Coast Sound School.

[1] In September, after the formal end of World War II, she moved up to San Francisco where she was decommissioned on 30 October 1945.

[1] Her name was struck from the Naval Vessel Register on 13 November 1945; and in December 1946, her hulk was sold for scrapping to the Salco Iron and Metal Company of San Francisco.