Yes — Japanese midget submarines were already around Pearl Harbor more than an hour before the first planes arrived on December 7, 1941. Five two-man subs launched to sneak into the harbor and fire torpedoes during the air raid. The plan failed: the destroyer USS Ward sank one at about 6:45 a.m. — the first American shot of the war — and the rest were lost or captured.
Key Highlights
- Five Japanese Type A midget submarines (78 feet long, two crew, two torpedoes each) were launched from five mother submarines about 10 miles off Oahu before dawn.
- The destroyer USS Ward sank one at roughly 6:45 a.m. — more than an hour before the air attack — firing the first American shots of the Pacific War.
- The midget submarine mission was a failure: none is confirmed to have damaged a U.S. ship, and all five subs were lost.
- Ensign Kazuo Sakamaki, washed ashore near Bellows on December 8, became the first Japanese prisoner of war of World War II.
- The submarine base at Pearl Harbor survived the attack untouched — and U.S. submarines went on to devastate Japanese shipping across the Pacific.
The Plan: A Secret Underwater Strike
Before a single Japanese aircraft took off on December 7, 1941, an advance force was already moving toward Pearl Harbor underwater. Japan’s plan called for five Type A Ko-hyoteki midget submarines — each about 78 feet long, crewed by just two men, and armed with two torpedoes — to slip into the harbor under cover of darkness, hide until the air raid began, and then surface and fire on the U.S. capital ships anchored along Battleship Row.
The subs were carried piggyback-style on five large mother submarines (I-16, I-18, I-20, I-22, and I-24) and released around 3:00–3:30 a.m., roughly ten miles off the harbor entrance. The two-man crews were among the navy’s most carefully selected volunteers, and the operation was kept so secret that most of the Japanese fleet didn’t know it was happening. Even so, not everyone in the Japanese high command liked it. Air strike leader Mitsuo Fuchida worried that the subs would be spotted and give away the surprise — a fear that turned out to be justified. For a broader overview of the attack’s scale and casualties, see our facts about Pearl Harbor.
December 7, 1941: What the Submarines Actually Did
The USS Ward Fires the First American Shot
The first combat of the Pacific War happened not in the air but at sea, over an hour before the bombs fell. Around 3:42 a.m., the minesweeper USS Condor reported a periscope near the harbor entrance. At roughly 6:37–6:45 a.m., a PBY patrol plane spotted a submarine’s wake trailing the cargo ship USS Antares, and the destroyer USS Ward — commanded by Lt. William Outerbridge, who had taken command only days earlier — opened fire at point-blank range. Her No. 3 four-inch gun hit the midget submarine’s conning tower, and the sub sank almost immediately.
It was the first American shot fired in World War II. But Pearl Harbor’s command dismissed the report as another false alarm — one of many that jittery December morning — and no general alert went out.
One Sub Gets Inside the Harbor
At least one midget submarine did penetrate the harbor entrance. Around 8:30 a.m., as the air attack raged, the destroyer USS Monaghan spotted it, rammed it, and dropped depth charges, sinking the craft. Despite decades of study, historians have not confirmed that any midget submarine managed to fire its torpedoes successfully at a U.S. warship that day. The destruction — 2,403 Americans killed and the Pacific Fleet’s battleships shattered — was the work of the air raid, not the submarines. If you’re touring the battle sites, our guide to the battleships of WWII at Pearl Harbor walks through which ships were hit and what happened to them.
HA-19 and America’s First Japanese POW
The most famous of the five midget subs never made it inside the harbor at all. The HA-19’s gyrocompass failed almost immediately after launch, its navigator spent hours guessing, and it struck coral reefs three times. The destroyer USS Helm fired on it at about 8:17 a.m. — the shells missed but knocked it free from the rocks. Seawater leaking into the batteries produced toxic gas that repeatedly knocked out the crew. By the morning of December 8, the sub had run aground near Bellows Beach on Oahu’s east shore.
Crewman Ensign Kazuo Sakamaki crawled onto the sand unconscious. His crewmate, Kiyoshi Inagaki, drowned in the surf. Sakamaki woke to find himself facing the rifles of an American patrol and was taken prisoner by Hawaii National Guardsman David Akui — becoming the first Japanese prisoner of war of World War II. The captured HA-19 was dismantled, studied by Navy engineers, toured the country to sell war bonds, and today sits in the National Museum of the Pacific War in Fredericksburg, Texas.
A Failed Mission, and the Four Subs Still Missing
All five midget submarines were lost. Of the remaining two, one was found scuttled off the harbor entrance in shallow water — likely destroyed by its own crew when escape proved impossible. The sub sunk by the USS Ward wasn’t confirmed until 2002, when researchers found it about 1,300 feet down, carrying a shell hole consistent with Ward’s gunfire. For years, Ward’s crew had been doubted; the wreck proved they were right.
Historians still argue over details — there is long-standing debate over whether one midget sub’s torpedoes actually struck anything — but the consensus is clear: the underwater assault accomplished essentially nothing. Japan lost 29 aircraft, 5 midget submarines, 55 airmen, and 9 submariners, with Sakamaki as the war’s first Japanese prisoner.
The Base That Survived — and Won the Pacific
Here is the irony the midget submarines never saw: the Japanese attack plan deliberately skipped Pearl Harbor’s repair facilities, fuel depots, and — crucially — the submarine base. Japan’s leaders believed the war would be short and smoke from burning oil would foul their aim anyway. The decision was a strategic blunder of the first order.
The untouched submarine base became the forward headquarters of America’s “Silent Service.” For the rest of the war, U.S. fleet submarines operating from Pearl Harbor ran down Japan’s merchant fleet and navy across the Pacific, cutting the island nation off from the oil and supplies it needed to fight. Most histories credit American submarines with sinking the majority of Japanese merchant shipping lost in the war. The underwater war Japan opened on December 7 was one America would win — decisively.
Visiting Today: The USS Bowfin Submarine Museum & Park
You can walk the deck of a real World War II submarine at Pearl Harbor. The USS Bowfin (SS-287), a Balao-class fleet submarine, was launched on December 7, 1942 — exactly one year after the attack — and earned the nickname the “Pearl Harbor Avenger.” She completed nine successful war patrols between 1943 and 1945, is credited with sinking 44 enemy vessels, and received both the Presidential Unit Citation and the Navy Unit Commendation. Designated a National Historic Landmark in 1986, she opened to the public in 1981 and now anchors the Pacific Fleet Submarine Museum on a 2.5-acre site just steps from the USS Arizona Memorial.
The experience is hands-on: you climb down into the cramped hull and walk through the torpedo rooms, galley, wardroom, and control room, all restored to their 1945 configuration — a self-guided audio tour is included. The 10,000-square-foot museum holds more than 4,000 artifacts, including a cutaway Poseidon missile, a Japanese Kaiten manned torpedo, and the conning tower of the USS Parche. Don’t miss the Waterfront Memorial honoring the 52 American submarines and more than 3,500 submariners lost during World War II.
Practical details: the museum is at 11 Arizona Memorial Drive, open daily 7:00 a.m.–5:00 p.m. (last entry 4:15 p.m.), closed New Year’s Day, Thanksgiving, and Christmas. Admission is $25.99 for adults and $14.99 for children ages 4–12; children under 4 are not permitted aboard the submarine. A typical visit takes about 1.5–2 hours. Plan it alongside the other memorials with our ultimate guide to visiting Pearl Harbor, or explore all the sites — from the Arizona and the Missouri to the Bowfin — in our Pearl Harbor historic sites guide.
Frequently Asked Questions
Did Japanese submarines attack Pearl Harbor before the planes arrived?
Yes. Five Japanese midget submarines were launched before dawn on December 7, 1941, to slip into the harbor and attack during the air raid. The destroyer USS Ward sank one at about 6:45 a.m. — over an hour before the first bombs fell — firing the first American shots of World War II.
What happened to the Japanese midget submarines at Pearl Harbor?
All five were lost. The USS Ward sank one before the attack, the USS Monaghan sank one inside the harbor, one (HA-19) ran aground and was captured, and the remaining two were found scuttled or on the seabed. Nine of the ten submariners died; Ensign Kazuo Sakamaki was captured.
Who was the first Japanese prisoner of war of World War II?
Ensign Kazuo Sakamaki, crewman of the midget submarine HA-19. After his sub ran aground near Bellows Beach on December 8, 1941, he was captured by Hawaii National Guardsman David Akui. His submarine is now displayed at the National Museum of the Pacific War in Fredericksburg, Texas.
Did the midget submarines damage any American ships?
There is no confirmed record of a midget submarine torpedo striking a U.S. ship at Pearl Harbor. The devastation of December 7 — 2,403 Americans killed, eight battleships damaged or sunk, 188 aircraft destroyed — was inflicted by the air attack. Historians consider the midget submarine operation a failure.
Can you go inside a submarine at Pearl Harbor today?
Yes. The USS Bowfin (SS-287), a World War II fleet submarine launched on December 7, 1942, is open to the public at the Pacific Fleet Submarine Museum next to the USS Arizona Memorial. Visitors tour the restored interior — torpedo rooms, control room, galley — with a self-guided audio tour. Children under 4 are not permitted aboard the submarine itself.
How much does it cost to visit the USS Bowfin Submarine Museum?
General admission is $25.99 for adults and $14.99 for children ages 4–12. The museum is open daily 7:00 a.m.–5:00 p.m. (last entry 4:15 p.m.) and is closed on New Year’s Day, Thanksgiving, and Christmas. Military and local kama’aina rates are available — check bowfin.org for current pricing before you go.