After the American Revolutionary War broke out in 1776, the Connecticut colonial government ordered the construction of Black Rock Fort (to be built on top of an older 17th-century fort) to protect the port of New Haven. In 1779, during the Battle of New Haven, British soldiers captured Black Rock Fort and burned the barracks to the ground. The fort was reconstructed in 1807 by the federal government (on orders from the Thomas Jefferson administration), and rechristened Fort Nathan Hale, after the Revolutionary War hero who had lived in New Haven. The cannons of Fort Nathan Hale were successful in defying British war ships during the War of 1812. In 1863, during the Civil War, a second Fort Hale was built next to the original, complete with bomb-resistant bunkers and a moat, to defend the city should a Southern raid against New Haven be launched. The United States Congress deeded the site to the state in 1921, and all three versions of the fort have been restored. The site is now listed on the National Register of Historic Places and receives thousands of visitors each year.

What structure was ordered to be built in New Haven in 1776 to protect the port at the outset of the Revolutionary War?