Located in the Hudson River near the town of Fishkill, Pollepel Island is a 6.5 acre, uninhabited, rocky island. It sits near the eastern bank of the Hudson, about 1,000 feet away.
The little island's post-colonization history includes being remarked upon by Dutch colonizers and playing a small role in the Revolutionary War. Located near West Point, the island sat next toa set of 106 cheval de frise, underwater barriers consisting of iron-tipped logs constructed using prison labor. The obstruction wasn't particularly successful--no English boats were sunk--but some of its cassions still sit at the bottom of the river. At one point during the war, George Washington suggested using Pollepel Island as a military prison, but it doesn't seem that ever happened.
In 1901, David Bannerman, the son of arms dealer Francis Bannerman VI, spotted (the supposedly haunted) Pollepel Island while on a canoeing trip and recommended it as a place for the family business to store their piles of weapons. Bannerman purchased the island for $1,600 (about $58,000 today--seems like a steal for a private island) from a member of the Taft family and began to set up an unusual warehouse. An added bonus? Rumors of hauntings had long swirled around the island.
For all my not-quite-concealed scorn for the business of selling arms, I think that the parts of the story related to the castle's construction is genuinely cool and interesting. So I'll get into that next time.
This post doesn’t link to sources as comprehensively as usual, because it's based on an old episode of Buried Secrets Podcast. I wrote this based on the original episode notes, which I penned when I was worse at adding specific in-line citations. But all of the sources I used are linked at the bottom of the episode shownotes page.