The fort idea reminds me of Manteo N.C. A nice little fort, were everyone disappeared into thin air.
Anyone remember the Alamo?
Forts have such logistic problems, same as today in city's sewage disposal, clean water and finding a way to get around the enemy to acquire supplies, food, clothing and opens itself up to the dead beats that will steal the gold from your teeth.
In the rock cellar of my family home the walls are grimy from when the home was burned down due to an Indian Attack , the Indians went on a rampage, burned a neighboring town of Wells Maine and continued down the coast. They came too fast for most to flee to safe areas, but being hard headed the stubborn Yankees rebuilt in the early 1700's their homes on the cellar site of burned out homes.
Sort of like today in the mid-West and after a tornado in a trailer park the people clean up the damage and haul in another trailer.
Don't like the idea of a society bunched in together, we well know what happens when a rumor goes around and next thing one knows they are burning people at the stake as Witches.
It is said that the safest people in the old west were the traders that were too valuable for anyone to kill or rob. Everyone Friend or Foe needed them so they were left alone. If someone on either side harmed them other traders would not come into the area.
Farmers up here were the wealthy but the job was a back breaking job subject to the weather. Fisherman were poor but at least they kept their belly's full of Lobster, clams, oysters, salt cod and Eels ETC. AND they could move about from place to place in an emergency, Farmers were stuck, no place to go. Too far from a fort for safety and only helpers were family and an occasional slave of all colors and country's to help out.
Taking a page from history, it was the humans that could bug out that survived.