time, and was done during a gale, both ships successfully refueled. Over the next several months the Mine Force planted mines in the North Sea along with their Allied counterparts. Shawmut took part in ten minelaying excursions, placing 2,970 mines for the barrage. Hostilities ceased on 11 November 1918. Shawmut then loaded 310 mines and set sail for the US with various other minelayers on 30 November. She reached Hampton Roads Naval Operations Base (NOB), Norfolk, Virginia, on 27 December 1918. Between the wars Shawmut was reassigned to the US Air Department after refitting at Boston Navy Yard to serve as a seaplane tender. The ship carried out the majority of her duties tending the amphibious aircraft off the eastern seaboard of the United States from Key West, Florida, to Narragansett Bay, Rhode Island. Her voyages frequently took her to foreign ports including: Guantánamo Bay, Cuba; Kingston, Jamaica; Samaná Bay, Dominican Republic; and Trujillo, Panama. On 17 July 1920, she was reclassified as CM-4 (Cruiser-Minelayer #4). In June and July 1921, Shawmut participated in an event that is a major milestone in military aviation history, now known as Project B. The experiences of Brigadier General Billy Mitchell during the war had caused him to become an outspoken advocate for the use of winged aircraft in military operations, which was then a new concept. He argued for the establishment of an independent air force and expanding the use of winged aircraft. His undiplomatic style hindered acceptance by his colleagues, among the beliefs of whom was that aircraft would be ineffective as weapons against contemporary military vessels. Mitchell proved them wrong during a series of bombing exercises in the summer of 1921, in the Hampton Roads, off the coast of Virginia. For a part of these, two US Army photographers from Langley Army Air Field joined Shawmut to document attacks on the captured German U-boat, , that was used as the first target. After participating in the bombing exercises, Shawmut returned to her routine as an aircraft tender for the rest of summer of 1921. She entered the Philadelphia Navy Yard for an overhaul on 31 October, where she remained until 5 January 1922. She then returned to her primary duties as a minelayer but also continued to provide services to Navy planes. The duties took her back to the Caribbean, as well as operating along the US east coast for battle