It took a whole lot of copper to make “Old Ironsides” shipshape again.

After a restoration process that took more than two years, the USS Constitution – first launched in 1797 and the oldest commissioned naval vessel still afloat – was eased back into Boston Harbor on Sunday night.

Called “Old Ironsides” because a British sailor reportedly shouted “Her sides are made of iron” after cannonballs bounced off the ship during the War of 1812, the process to float the USS Constitution began late Sunday afternoon when the dry dock in which she had been repaired began to be flooded, according to a statement from the U.S. Navy.

At about 9:45 p.m. ET, the ship was afloat in the dock. At about 11:15, it began moving into the harbor, the Navy said.

“This ship is the other woman in my life,” Paul Brawley, a retired Navy captain who was commander of the Constitution when its restoration began, told The Boston Globe. America’s heritage is “directly tied” to the ship, he added. “It’s historical. We are preserving an icon,” Brawley said.

According to the Navy, the $12 million project included replacing most of the ship’s copper cladding – a process that required 2,200 sheets – repairing the outside wooden planks and rebuilding 42 gun carriers throughout the ship. Refurbishment of the rigging and masts is to be done before the ship is due to reopens to visitors in August.

The USS Constitution, which was named by President George Washington, won three major battles during the War of 1812 against the United Kingdom, according to U.S. Navy magazineAll Hands.

The ship was retired from active military service in 1855, according toHistory.com, before becoming a training vessel and then a touring national landmark. Since 1934, the ship has been based at the Charlestown Navy Yard in Boston.

"All of the Detachment Boston employees take great pride in the work accomplished," said Richard Moore, Naval History and Heritage Command Detachment Boston director. "The ship restorers, riggers and blacksmith are a group of skilled craftspeople who have put their talents to great use during Constitution's dry dock restoration. Tonight's successful undocking is the culmination of the Detachment Boston's hard work on Old Ironsides over the past 26 months."