I recently went to Marblehead, MA for a few hours with my son, who was bicycling around Marblehead Neck. Among other things we went to Fort Sewall, which was built in 1742 to protect from potential French raiders. Not much of a fort, but easy to see from the pictures why it was built there, as it protected Marblehead Harbor. Marblehead was a big fishing port. Just to the north of the fort is the entrance to Salem Harbor and Beverly Harbor. I'm not sure if the fort in later times was ever meant to protect them or if it was too far from the sea lane. In 1814 the USS Constitution sailed into Marblehead Harbor under the fort's guns after its mainmast had split.
Attached are some pictures of the fort,in other posts following are pictures of the view from the edge of the fort, looking across the harbor more-or-less east southeast to Marblehead Light, and then out to the open sea.
The first three pictures are of the fort itself, from inside the park (There is a small parking area right nearby). A short trail leads to the park. The fourth picture is the sign at the start of the trail. The fifth picture shows the layout of the fort; was hard to take with the sunlight. If I find a better picture on the internet I will post later. The sixth picture is a commemorative stone of General John Glover, whose regiment of "fishermen" played two very important roles in the revolution: in getting the army off of Long Island onto Manhattan, and getting it across the Delaware. I read in the paper afterwards that while we there re-enactors were helping re-dedicate the newly built Glover School.