NORFOLK, Va. — Five Somali men accused of attacking a U.S. Navy ship off Africa’s coast were convicted Wednesday on federal piracy charges in what the government said was the first piracy conviction in a U.S. courtroom in nearly 200 years.

The verdict was handed down by a jury in U.S. District Court. The five men, who wore earphones, stood silently as the verdict was read to them by an interpreter. They face mandatory life terms at a sentencing hearing set for March 14 in Norfolk.

Attorneys for the five said they didn’t fully grasp the trial, the charges or the verdict.

“He really doesn’t understand fully,” said Jon N. Babineau, who represented Abdi Mohammed Gurewardher. “He does understand he will die in a U.S. prison. He understands that.”

“They were just sad,” said David Bouchard, who defended Abdi Wali Dire.

Defense lawyers had argued the men were innocent fishermen who had been abducted by pirates and forced to fire their weapons at the ship.

But federal prosecutors argued during trial that the five had confessed to attacking the USS Nicholas on April 1 after mistaking it for a merchant ship. The Nicholas, based in Norfolk, was part of an international flotilla fighting piracy in the seas off Somalia.

The government said the conviction should send a message to pirates who continue to harass merchant ships off the coast of Africa and take hostages.

“Certainly we hope the word goes forth that armed attacks on U.S.-flagged vessels are crimes against the international community and will not go unpunished,” U.S. Attorney Neil H. MacBride said during a teleconference after the verdict.

Piracy and maritime law experts said news of the convictions would reach across the globe.

Ken Randall, dean of the University of Alabama School of law and a piracy scholar, wrote in an e-mail that the verdict set an important example for the world.

“On the seas, as well as in the courts, every nation should follow the US lead in redressing piracy,” he wrote.

The government said three of the men were in a skiff that opened fire on the Nicholas with assault rifles, then fled when sailors returned fire with machine guns.

All the men later confessed to the attack to an interpreter aboard the Nicholas. He said they expected to make anywhere from $10,000 to $40,000 from the ransom.

Defense attorneys said it is not uncommon in virtually lawless Somalia for pirates to capture fishermen and essentially enslave them, forcing them to either do their bidding or be killed. They said that’s what happened to their clients.

The attorneys argued that the men — Dire, Gabul Abdullah Ali, Gurewardher, Abdi Mohammed Umar and Mohammed Modin Hasan — had actually hoped to be rescued.

They also questioned the validity of the confessions, which were not videotaped.

However, Lt. j.g. Chad Robert Hutchins, who was in charge of security aboard the Nicholas when it was attacked, praised the verdict.

“Our justice system is great,” he said outside of court after the verdict was read. “It’s a great feeling.”

He described the mood on the ship that morning as one of fear. “People were scared,” he said. “People were jumping under things, people were laying on the ground, people were hiding behind things. There was definitely fear on the ship.”

Other countries have recently held piracy trials, but legal and maritime scholars say one of the last in the U.S. was in 1861, when 13 Southern privateers aboard the schooner Savannah were prosecuted in New York City. The jury deadlocked and the men were later exchanged with the South.

The last U.S. conviction for piracy was in 1819, and involved a foreign vessel. U.S. piracy law was based on that case.

Besides piracy, the five were convicted of plundering, weapons, assault, explosives and conspiracy charges. They were also armed with a rocket-propelled grenade.

Somalia’s first secretary to the U.N. mission called the trial “vigilante justice” and said he would appeal for an international solution to deal with piracy.

“One of the things we’re asking is to have those convicted of piracy to be returned to Somalia so they can serve their terms,” said Omar Jamal.

MacBride said that was unlikely.

The government is prosecuting a separate group of Somali defendants for an alleged April 10 attack on the USS Ashland, also off Africa. A judge in Norfolk dismissed the piracy charge, but the government is appealing.