A warship submerged for two centuries in a river near Washington, D.C., could provide new insight into the relatively obscure War of 1812, say archaeologists who are preparing to excavate the wreck.

The war started because the British, who had been fighting with France since 1803, imposed restrictions on U.S. trade with the French, infuriating Americans. Relations worsened when British ships began intercepting U.S. vessels on the high seas, removing any British-born sailors, and forcing them to serve in the British navy.

The U.S. Congress declared war on the British—including their Canadian colonists—in June 1812.

Scientists have known about the unidentified wartime shipwreck, which lies in the Patuxent River about 20 miles (32 kilometers) from the nation's capital, since the early 1970s. (Related: "Blackbeard's Ship Confirmed off North Carolina.")

In the 1980s archaeologists removed a few artifacts from the site that suggested the wreck might be the remains of the U.S.S. Scorpion, the flagship of the Chesapeake Bay Flotilla, which staged daring hit-and-run attacks against British invaders during the war.

The entire flotilla, including the Scorpion, was deliberately sunk in the Patuxent in 1814.

Starting in early 2013, archaeologists with the Maryland State Highway Administration, the U.S. Naval History and Heritage Command, and the Maryland Historical Trust will build a temporary watertight container called a cofferdam around the wreck, pump the water away, and start detailed excavations.

Thanks to ideal preservation conditions in the river, experts examining the wreck will be able to "pull back the layers of time," said Julie Shablitsky, an archaeologist with the Maryland State Highway Administration.

Preliminary work has already yielded about 200 artifacts in excellent condition, including medical supplies, coins, and an instrument that was used to extract teeth, Shablitsky said.

The scientists think they could also find small arms, ammunition, cutlasses, and maybe even larger guns such as cannons. (Related pictures: "Mystery Shipwreck Found With Muskets, Beer Bottles.")

"Everything there is in great condition—intact wood, leather," Shablitsky said. "We're preparing ourselves for a time capsule containing everything you would have needed to fight a world superpower 200 years ago."

Scuttling the Fleet

Although the Chesapeake Bay Flotilla could never have defeated the British navy, from April to August of 1814, the little armada effectively harassed British forces.

The fleet of 18 ships carried only a couple guns each against the heavily armed British vessels. But the smaller U.S. ships were much more maneuverable, said Robert Neyland, director of the Underwater Archaeology Branch of the Naval History and Heritage Command.

And because they could operate in shallower water than the larger British ships, the U.S. fleet could escape into creeks and other waterways that were inaccessible to their opponents, Neyland said.

The Chesapeake Bay Flotilla's attacks so enraged the British that they launched a devastating campaign of plundering and burning along coastal Maryland.

British ships eventually trapped the fleet in the Patuxent River near Wayson's Corner, Maryland. On August 22, 1814, the flotilla was scuttled to prevent it from falling into enemy hands.

The British defeated a U.S. force at Bladensburg, Maryland, on August 24. That same day, British forces entered Washington, D.C., and set fire to the White House and the U.S. Capitol.

Despite these setbacks, U.S. naval victories on the Great Lakes hampered the British war effort. And American forces turned back a British invasion of Baltimore's Fort McHenry in September 1814, inspiring Francis Scott Key to pen what's now the U.S. national anthem, "The Star-Spangled Banner."

By the winter of 1814, both sides were ready to talk peace. Today historians debate the long-term effects of the war, since neither the U.S. nor Great Britain lost territory in North America.

Ship Protected by Storm?

Although the Patuxent shipwreck is nearly 200 years old, it's still in excellent shape, thanks to a confluence of conditions, Neyland said.

For starters, a powerful hurricane that swept up the East Coast in September 1821 pushed a huge storm surge up the Chesapeake Bay and its tributaries, according to Jeff Masters, director of the Weather Underground website.

This surge probably covered the wreck with sand and mud, keeping away air and sealing the wooden vessel from the ravages of time.

The cool fresh water of the Patuxent also helped because, had the wreck been in warmer salt water, chemical reactions would have caused more disintegration, Neyland said.

In addition, since the ship lies less than ten feet (three meters) deep, the wreck hasn't been subjected to that much water pressure, he said.

Stand Up and Fight

Archaeologists are now doing preliminary work to determine the outline of the wreck. The cofferdam will be built next April, and excavations will take about five months.

After the artifacts are removed, the wreck will be covered back up with silt, because funds aren't available to raise and restore the ship.

In general, the War of 1812 and the Chesapeake Bay Flotilla can tell us "something about early American history that we didn't know before," said the Maryland State Highway Administration's Schablitsky.

"The American Navy was very, very young, and it was going against a global superpower," she said.