Sad Sydney Submarine Secret of Sexty!

It's a story I've heard before. It is family lore. However, this time, it takes on a new perspective. This time, I'm about to attend the funeral of one of the last remaining witnesses. His daughter is recounting the story after being picked up from the airport by another witness and me.

“Why won't anyone tell the story?” is the repeated lament. So I take it up.

The untold secret story involves the sinking of the HMAS Kuttabul in Sydney Harbour, at 00:30 on 1 June 1942 which resulted in the loss of 27 lives: 19 Australian, 2 British and 6 Japanese.

Japanese Submarine Sinks Kuttabul In Sydney 1942 Untold Story - The Sunk Kuttabul

The Told Story!

That night, 3 Japanese midget submarines, launched from a fleet of larger submarines offshore, had sneaked into the depths of a secure Sydney harbour.

Two midget submarines were spotted, chased and attacked, leading the two-man crews to commit suicide, Australian national archives record. One of the submarines was restored and is a feature display in Australia's premier War Museum in Canberra.


Japanese Submarine Sinks Kuttabul In Sydney 1942 Untold Story - Raising Destroyed Midget Sub

The third fired 2 torpedos at a US heavy cruiser, the USS Chicago. They both missed, but one exploded beneath the HMAS Kuttabul behind it.

That submarine then slipped out of the harbour; some say it had been damaged and doubted whether it survived.

Japanese Submarine Sinks Kuttabul In Sydney 1942 Untold Story - Destroyed Midget Sub on Way to War Memorial in Canberra

Update: The missing M24 Japanese Type A 'Ko-Hyoteki' midget submarine, was found in November 2006 after about 65 years. A group of amateur divers discovered the vessel upright on the seabed in deep water about five kilometres (3.1 miles) off Sydney's northern beaches. It had been damaged. “The submarine is of international historical significance and is presumed to still contain the remains of its commander and navigator, Sub-Lieutenant Katsuhisa Ban and Petty Officer Memoru Ashibe," the government said. The authorities decided the bodies would remain undisturbed on the seabed in their craft, which has been declared protected under Australia's Historic Shipwrecks Act.

Shock waves spread throughout Australia and its Allies at this “surprise attack” on Sydney Harbour

Japanese Submarine Sinks Kuttabul In Sydney 1942 Untold Story - The Last Midget Sub Found

The Untold Secret Story!

The sad truth is that it was no surprise at all – at least to some!

The story tells how people knew about this attack in advance, and then covered it up after!

"The Japanese sub attack was significant as Sydney was so far away from the main theatre and the Japanese were able to come this far south and launch an attack on our largest city," says Australian National University's David Horner (

"You've got to remember Australia had a population of seven million people in World War II, so we felt very vulnerable. There was a real legitimate concern in early 1942 that Australia might be invaded," Horner said.

Australia was invaded! After Australia entered the war in 1941, up until mid 1943, the Japanese launched a prolonged campaign of bombing raids on mainland Australia, notably 19 February 1942 on Darwin, and a submarine campaign centred along the East coast – attacking North-bound supply ships that regularly left Sydney on Sundays.

A Japanese mother submarine and her midget submarines had been using a section of coast North of Sydney as their base. The men would come ashore and have rations on the beach.

One day, the remains of their camp was discovered by men manning an Observation Post that had been set up primarily for early warning to Sydney. The activity was reported to Sydney and when the vessels headed south towards Sydney the following day, it was reported yet again.

In Sydney, the reports were not taken seriously. A surprised Sydney Harbour was attacked and men lost their lives.

The following day, three men from Sydney HQ, dressed in suits, visited the Observation Post and took all log books. The members of the Observation Post were told not to mention it.

Japanese Midget Submarine was spotted from this spot prior to sinking HMAS Kuttabul in Sydney Harbour in 1942

Why the Story Has Not Been Told

Understanding the man behind the story helps understand why it has not been told.

Born in 1889, Ivo Errol Sexty was brought up with country privilege in Tamworth as a fiercely loyal, devoted and patriotic man. His WW1 Regimental Army Number of 128 attests his eagerness to serve the country. Many stories have been told of him taking the first load of horses to Egypt with the 1st Veterinary Section and his terrible experiences in the trenches in the Somme. He was mentioned in despatches (twice) and has the Belgium War Cross.

After the war, he established himself as an orchardist in Wamberal, just near Gosford, North of Sydney. However, when WWII started, despite attempting some tricks to serve again, he was told he was too old to enlist again. Instead, he was asked to establish the Volunteer Air Observer Corps. The aim was to provide early warning to Sydney of any approaching enemy aircraft.

Later, as the Japanese increased activity along Australia's coast, the mission was extended to include any observed maritime activity.

As a deeply patriotic man, Mr Sexty refused to tell of the incident because of “national security”. Now that he, and most of the others have now faded, another witness, and the family, speak out.

Surviving Witness Tells the Family Secret Story

Click the links below to watch a video of Diana Coombe (nee Sexty) tell the secret story of the Japanese submarine attack on Sydney Harbour. (Recorded 5 September 2009)

The Playlist (plays the interview in 2 parts - follows automatically)

Part 1: 

Part 2:

The full 18:39 unedited video (38Mb):