Guard-Ship
GUARD-SHIP, a warship stationed at some port or harbour to act as a guard, and in former times in the British navy to receive the men impressed for service. She usually was the flagship of the admiral commanding on the coast. A guard-boat is a boat which goes the round of a fleet at anchor to see that due watch is kept at night.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)