The "Sargo"-class submarines were among the first US submarines to be sent into action after the Japanese attack on Pearl Harbor, starting war patrols the day after the attack, having been deployed to the Philippines in late 1941. Similar to the previous , they were built between 1937 and 1939. With a top speed of 21 knots, a range of (allowing patrols in Japanese home waters), and a reliable propulsion plant, along with the "Salmon"s they were an important step in the development of a true fleet submarine. In some references, the "Salmon"s and "Sargo"s are called the "New S Class", 1st and 2nd Groups.