Its mission was to protect the Merrimack River and Newburyport Harbor from possible air and naval attack.

[3] It was north of the intersection of Route 1A and the coast road, in front of the line of beach houses.

It provided target data to the 16 in (406 mm) guns of Battery Seaman at Fort Dearborn as Base-End Station No.

[1] Other fire control sites for HD Portsmouth in Massachusetts were at Plum Island,[5] Crane Beach,[6] and Halibut Point.

[2] The reservation was returned to the Commonwealth in 1945; the fire control station became a Massachusetts State Police barracks until it was destroyed by a storm on 2 April 1958.