Veterans of the US boat that destroyed a Japanese submarine off the Oahu coast on December 7, 1941 met at Pearl Harbour this weekend to revisit the day when the first shot of the Pacific war was fired.

Almost an hour after the USS Ward attacked the midget sub, 40 Japanese torpedo bombers made their first successful and unhindered run on Pearl Harbour's Battleship Row.

Veterans, their families and government and military officials are remembering the Ward in anticipation of Wednesday's observance of the 64th anniversary of the attack, which pushed the United States into World War II.

The Ward, then a newly recommissioned World War I destroyer, shot the Japanese vessel in the harbour's defensive area, where submarines were required to sail above water.

Will Lehner, 84, whose battle station on the Ward was as ammunition handler on the destroyer's afterdeck, said the vessel sailed over the 78ft black Japanese sub after it sunk.

"It looked like it was covered by moss," said Lehner, who now lives in Stevens Point, Wisconsin. "I had never seen anything like it before."

However, proof of the attack did not appear until 2002, when University of Hawaii researchers found the missing sub submerged in about 1,200ft of water.

"Every time we would tell someone about it, they would say 'You have no proof'," Lehner said. "It was a closure for me to see that sub. I saw it when it got hit, I saw it when it was going down, and then, 60 years later, I saw it laying on the bottom."

The Japanese sub sunk by the Ward was one of five launched on December 6, each carrying a two-man crew and armed with two torpedoes. One of them washed up on the beaches at Bellows after the 1941 attack; three, including the one attacked by the Ward, were believed to have been sunk; the whereabouts of the fifth have never been verified.