Why is Fort Adams in the shape of a pentagon? It goes back to 15th-century Europe.

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When Washington, D.C., burned in the War of 1812, it was clear there were some holes in the national defense plan.

Determined to correct them, President James Monroe made it a part of his inaugural address in 1817. To help it along, he added Simon Bernard, Napoleon’s former aide-de-camp, to a board created the year before to help devise the nation's first unified coastal defense system.

In 1821, the board came out with a plan to build more than 40 fortifications, and one of them was Newport’s Fort Adams. Work started on the fort in 1824.

The fort celebrates its 200th anniversary this year, but its time standing sentry over Narragansett Bay is long over. Today, it’s open for tours, picnics and concerts as Rhode Island's second-most-visited state park.

But a What and Why RI reader wrote in with a question about the fort that relates back to its original purpose: “Why is Fort Adams pentagon shaped?”

An aerial photo of Fort Adams in 1964.
An aerial photo of Fort Adams in 1964.

History of pentagon-shaped forts

This goes back to Bernard, and Monroe’s decision to add a European to the design team.

“Bernard was schooled in the Vauban style of fortification and became the head of the fortification committee, designing the majority of the defenses,” said Robert McCormack, the director of visitor experience at Fort Adams.

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Pentagonal forts, which are also called bastion or star forts, evolved alongside cannons in the mid-15th century, according to McCormack. They started in Italy but quickly became popular in France. By the 16th century, a French architect, the Marquis de Vauban, modified the style.

“One of the key advantages of having a pentagonal shaped, or bastion fort is that there are no areas on the perimeter of the fort in which an attacker could find refuge,” McCormack said in an email. “Should an army attempt to storm a Vauban-style fort, the defenders would engage them from multiple directions. Not only must an attacking army face fire from the front, but the pentagon shape also means defenders can expect to come under fire from the flanks as well.”

Why is Fort Adams pentagon-shaped?

Given the location of Brenton's Point at the mouth of the Bay, it was a natural spot for a fort. In fact, one had already been built there.

Maj. Louis Tousard had designed an “irregular open work at old Brenton’s Point sited so that about twenty guns could cover the East Passage and an equal number fire in the direction of Newport,” according to the Fort Adams Trust, which opened in 1799. It was named Fort Adams after President John Adams.

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That fort was considered “worse than useless,” when Bernard’s team got to it. Instead, they favored the pentagon design Bernard was accustomed to from Europe. Lt. Col. Joseph Totten arrived to supervise the work in 1825.

Totten did have to make a modification based on the geography.

“Fort Adams, however, as with several other forts of its era, is not a true polygon,” McCormack wrote. “As Fort Adams was designed to repel a foreign attack by land and sea, the military architects opted to ‘squeeze’ the fortification into the north end of the peninsula to prevent the option for an enemy land assault on all but its southern end.  Additionally, placing the fort at the end of the peninsula allowed the architects to extend seaward defenses while shortening and modifying the rest of the fortification to fit the terrain.”

And so, it became a slightly irregular polygon, but definitely an improvement over the “irregular open work.”

How to visit Fort Adams

A portion of the walking trail around Fort Adams, which was built as part of the nation's first unified coastal defense system.
A portion of the walking trail around Fort Adams, which was built as part of the nation's first unified coastal defense system.

The park, owned by the state, is free to visit, but the fort itself, a National Historic Landmark, is operated through the nonprofit Fort Adams Trust.

Guided tours and self-guided tours are available seasonally for a fee.

For the 200th anniversary celebration, a series of special events, including lectures, tours and fundraising events, will be happening in 2024. For more information, visit FortAdams.org.

What and Why RI is a weekly feature by The Providence Journal to explore our readers' curiosity. If you have a question about Rhode Island, big or small, email it to klandeck@gannett.comShe loves a good question.

This article originally appeared on The Providence Journal: Fort Adams in Newport, RI, is pentagon shaped by European design