Fort Elfsborg (1643-1651) - A Swedish Colonial Fort established in 1643 near Oakwood Beach, Salem County, New Jersey. Abandoned in 1651. Also Known as Fort Nya Elfsborg, Fort Edinburgh and Fort Myggenborgh (Mosquito Castle).
Established in 1643 by New Sweden's Governor Johan Printz as a three-cornered earthen redoubt armed with eight 12-pounder cannons and one mortar. Built to counter the Dutch Fort Nassau. The fort was poorly sited and the multitudes of mosquitos and gnats made life difficult for the garrison of 14 soldiers and 5 officers.
The Swedes abandoned and burned down the fort in 1651 after the Dutch built Fort Casimir across the river.
The actual site is now underwater off Elsinboro Point near Salem, New Jersey. A black stone monument (from Sweden) was dedicated in 2004 at the Elsinboro Township School.