The United States L-class submarines were a class of 11 coastal defense submarines built 1914–1917, and were the most modern and capable submarines available to United States Navy when the country entered World War I. Despite being considered a successful design by the USN, war experience in European waters demonstrated that the boats lacked the range, speed, and endurance to conduct extended patrols in the North Atlantic.

The Portsmouth Naval Shipyard, often called the Portsmouth Navy Yard, is a United States Navy shipyard on Seavey's Island in Kittery, Maine, bordering Portsmouth, New Hampshire. The naval yard lies along the southern boundary of Maine on the Piscataqua River.