GROTON, Conn. (July 31, 2021) The pre-commissioning unit (PCU) Hyman G. Rickover (SSN 795) seen prior to a christening ceremony at General Dynamics Electric Boat shipyard facility in Groton, Conn., July 31, 2021. Rickover and crew will operate under Submarine Squadron (SUBRON) FOUR whose primary mission is to provide attack submarines that are ready, willing, and able to meet the unique challenges of undersea combat and deployed operations in unforgiving environments across the globe. (U.S. Navy photo by John Narewski)