Vigilant was built as the private motorboat Marguerite II in 1909 by Henry L. Blatz at Philadelphia, Pennsylvania.

[1] The U.S. Navy acquired her from her owner in 1917 for use as a section patrol vessel during World War I.

For the remainder of World War I, Vigilant patrolled the Delaware Bay and the Atlantic coast of the United States from Atlantic City, New Jersey, to the mouth of the Chesapeake Bay.

She also carried messages, men, and mail to ships and stations within the 4th Naval District.

Occasionally, she ventured out to sea to search for survivors of torpedoed merchant ships, as she did on 9 June 1918 after a German submarine had sunk SS Del Rio.