An hour and 10 minutes before Japanese planes swooped down on an unsuspecting Pearl Harbor, the destroyer USS Ward fired on a submarine outside the harbor in what was known as the defensive sea area.

It was 6:45 a.m. on Dec. 7, 1941, and the submarine wasn’t supposed to be there. Hours earlier, at 3:42 a.m., the minesweeper USS Condor had spotted a periscope just under two miles from the Pearl Harbor entrance.

Now the Ward, crewed by naval reservists from Minnesota, was on the hunt.

The ship’s captain, Lt. William Outerbridge, “appeared on deck wearing a kimono over his pajamas,” said Thurston Clarke in “Pearl Harbor Ghosts.” “A gunner asked him, ‘Captain, what are we going to do?’ and Outerbridge, showing a decisiveness lacking in other officers during this final hour, responded, ‘We are going to shoot.’”

The older four-stack destroyer fired guns 1 and 3, and began dropping depth charges. The shot from the No. 3 gun hit the sub at the waterline at the base of its conning tower.

At 6:53 a.m., Outerbridge radioed the 14th Naval District Headquarters in Pearl Harbor: “We have attacked, fired upon and dropped depth charges upon submarine operating in defensive sea area.”

The submarine had slipped beneath the waves.

For the next hour, the skepticism of a Japanese attack on Pearl Harbor that had plagued command decisions before the onslaught continued to be the response until planes swarmed in the sky.

“Instead of electrifying its recipients, causing sirens to sound, pilots to dash to their planes, and warships to put to sea, Outerbridge’s message touched off a round of telephone calls,” Clarke wrote.

Rear Adm. Claude Bloch, commander of the 14th Naval District, was finally notified. So was Adm. Husband E. Kimmel, head of the U.S. Pacific Fleet, who had risen early for golf.

“Kimmel was not at all certain that this was a real attack,” Gordon W. Prange, Donald M. Goldstein and Katherine V. Dillon said in “At Dawn We Slept.” There had been false reports of submarines before in nearby waters.

Five 78-foot Japanese midget submarines launched from larger subs were supposed to lie submerged in Pearl Harbor and attack in concert with carrier-based airplanes.

No anti‑submarine nets were in place at Pearl Harbor, but anti‑torpedo nets were intended to prevent a submarine outside from firing torpedoes into the harbor.

The attack was unsuccessful, although some of the twin 18-foot torpedoes carried by the two-man subs were fired.

Among the many shortcomings that day, Clarke notes that Bloch “neglected to call Fort Shafter and inform the Army that a hostile submarine might have been sunk off Pearl Harbor.” The Army had the job of protecting the Pacific Fleet in Hawaii.

In 2002, the University of Hawaii’s Undersea Research Laboratory located the sub sunk by the Ward sitting upright in more than 1,200 feet of water several miles outside Pearl Harbor.

A four-inch round fired by the Ward had punched through both sides of the conning tower, likely killing the crew. It was confirmed, decades later, that Ward had struck the first blow in the Pearl Harbor attack.

Both torpedoes were still in their tubes, and both crew members are believed to be entombed within the sub, a ghost from Japan’s mostly successful surprise attack on Pearl Harbor.