‘Air raid, Pearl Harbor. This is not a drill.’

At about 5:50 a.m. on Dec. 7, 1941, six Japanese aircraft carriers 220 miles north of Oahu turned into the wind in high swells, preparing to unleash an aerial attack on America that would change the course of world history.

The airmen donned head scarves with the word “Hissho” (Certain Victory), and on that Sunday morning, it would be just that. The Japanese air armada and its “Operation Hawaii” was about to catch the U.S. Pacific Fleet and Oahu’s defenders unaware.

Flying off the carriers as part of the first wave of attackers were 43 fighters, followed by 49 high-level bombers. Next came 51 dive bombers and 40 torpedo planes. Eventually sighting Pearl Harbor, Cmdr. Mitsuo Fuchida, the air attack leader, gave the attack signal — To, To, To — shorthand for to­tsugekiseyo (charge).

History is not clear as to exactly when the fateful attacks occurred. Pearl Harbor historian John Di Virgilio said the very first base attack came about 7:46 a.m. at the Kaneohe Bay Naval air station, where 33 PBY reconnaissance planes were on the ground and in the bay.

“Zero fighters actually get over Kaneohe just a smidgen before” Wheeler Field was hit, Di Virgilio said. He placed the Wheeler attack at about 7:47 a.m. Bellows Field was strafed after Kaneohe.

“Those guys are a good six minutes, seven minutes, before the attack on the harbor itself,” Di Virgilio said. The strike on Pearl Harbor began between 7:53 and 7:55 a.m.

Dive bombers, high-level bombers and torpedo planes tore apart the harbor. Aviation Ordnanceman 1st Class Ted Croft was killed when a bomb hit Hangar 6 on Ford Island. Winging low across Pearl Harbor, Lt. Jinichi Goto lined up on the exposed battleship Oklahoma, which was outboard of the Maryland.

“I was about 20 meters above the water when I released my torpedo,” Goto said later. “As my plane climbed up after the torpedo was off, I saw that I was even lower than the crow’s nest of the great battleship.”

It was a surreal experience on a sleepy Sunday morning that initially defied explanation. Even with bullets and bombs falling, many still thought it was a training snafu.

Seaman Robert Osborne on Ford Island mused to himself, “Boy, is somebody going to catch it for putting live bombs on those planes!”

On the battleship USS Nevada, band leader Oden McMillan played on — even as a Japanese plane dropped a torpedo nearby.

“McMillan realized what was happening, but the years of training had taken over — it never occurred to him that once he had begun playing the national anthem, he could possibly stop,” Walter Lord wrote in “Day of Infamy.”

On the USS New Orleans, crew members smashed open ammunition boxes with fire axes. Aboard the USS Pennsylvania, a gunner’s mate used a big hammer to knock off locks. He had faced Japanese bombing on the U.S. gunboat Panay in 1937 in China, and he “announced he wasn’t going to be caught again,” Lord said.

The alarm was no sooner given than the USS Oklahoma and USS West Virginia took the first of nine torpedoes each, according to historians.

At 7:58 a.m., Lt. Cmdr. Logan Ramsey, who was in the Ford Island command center, ordered the message to be sent out that would resonate through history: “AIR RAID, PEARL HARBOR. THIS IS NOT A DRILL.”

The largest loss of life occurred when a 1,760-pound armor-piercing bomb blew apart the bow of the USS Arizona when the warhead ignited fuel and gunpowder. A total of 1,177 men died on the Arizona. It was and still is the single greatest loss of life at sea in U.S. Navy history.

On board the light cruiser USS Honolulu, Ray Emory manned a 50-cal. machine gun at one of the best sighting spots in the harbor, according to Di Virgilio.

Crew members on four guns on that side of the ship, 45 feet off the water, fired thousands of rounds. Five of the last seven torpedo planes swooping through were brought down, he said.

“We don’t know who’s who” with the kills, “but Ray’s group had the best line of them all,” Di Virgilio said.

A second wave of 167 Japanese planes — minus torpedo bombers — attacked at about 9 a.m. In the two attacks, fighters and dive bombers hit the airfields at Kaneohe, Hickam, Marine Corps Air Station Ewa, Bellows and Wheeler. In just over two hours, most American air power in Hawaii was destroyed.

“The Japanese caught the Hawaiian Air Force completely by surprise,” according to a history put together by Pacific Air Forces. “There was no coordinated, systematic, island-wide air defense that morning. Instead, 14 individual pilots attempted to engage the enemy with varying degrees of success.”

Amid the chaos, the tales of America’s fighting spirit and individual heroism that day are endless.

With Battleship Row a mass of flames and smoke, Cmdr. Duncan Curry stood on the bridge of the USS Ramapo and fired a 45-cal. pistol at attacking Japanese planes, tears streaming down his face, according to Lord.

In Kaneohe, Chief Petty Officer John Finn, an aviation ordnanceman, manned a 50-cal. machine gun on a stand in an exposed section of the parking ramp while under heavy Japanese strafing fire.

Finn, who later received the Medal of Honor, was wounded more than 20 times by shrapnel and took a bullet to the arm, but still fired back for 2-1/2 hours.

The Navy puts the U.S. fatality count from the attack at 2,403, including 68 civilians. Historians now believe the number of civilians killed is actually between 48 and 60. Twenty-one Pacific Fleet ships had been sunk or damaged, and 75 percent of the planes on surrounding airfields were damaged or destroyed.

The Japanese lost 29 aircraft — nine in the first wave and 20 in the second — in which 56 aviators were killed. Five two-man Japanese midget submarines were sunk, captured or abandoned.