The collection of the Queensland Maritime Museum in Brisbane
includes a remarkable exhibit— frigate HMAS Diamantina.
This humble ship can be rightly called a unique monument
to an important part of the world's naval history.
That's because she is the last remaining representative of the River-class ships,
which became famous for their contribution to the Battle of the Atlantic in World War II.
Naval Legends River-class frigates
On September 3, 1939, several hours after Great Britain had declared war on Germany,
a German U-boat sank the British cruise liner Athenia.
Two weeks later aircraft carrier HMS Courageous was torpedoed.
Thus began the Battle for the Atlantic
that was mainly fought between German U-boats,
Allied transport convoys, and their escorting ships.
The escorts that they were using at that stage for the convoys
were small destroyers mostly left over from WWI and very small corvettes and sloops.
These older warships were unable
to handle the conditions of the North Atlantic weather-wise,
but also did not have the endurance to be able to escort a convoy
all the way across the Atlantic from Great Britain
to the East Coast of the United States.
At the beginning of the war, the convoys carrying vital supplies to Great Britain
sailed from the USA and Canada virtually unprotected
and very often fell prey to German U-boats.
Only in the 200-mile area near the British Isles,
the so-called Western Approaches,
screening ships met the convoys and escorted them to British ports.
They needed a ship built especially for the sole purpose
of protecting transport convoys.
This type of ship wouldn't bombard coastal defenses
or fight against enemy surface targets.
It would only engage German U-boats and protect transports in a convoy.
It wasn’t long before a project was developed that met all the requirements.
The ship had a great cruising range
and was so different from the vessels that usually escorted convoys
that the Admiralty brought back a term from the era of sailing ships—the frigate.
As the majority of ships were named after British rivers,
the entire series became known as the River-class.
The River-class project had an important advantage—
the ships could be constructed by both specialized military shipyards
and civil shipbuilding enterprises.
SPECIFICATIONS of the River-class frigate HMAS Diamantina
Length: almost 92 meters
Beam: more than 11 meters
Draft: 4 meters
Displacement: 2,200 tons
Armament:
Primary armament: 2 dual-purpose 102-mm Mark XVI guns
Anti-aircraft artillery: 3 Bofors guns, caliber 40 mm
4 Oerlikon guns, caliber 20 mm
Anti-submarine armament:
4 depth charge rails and 150 depth charges in storage
The main power plant consisted of two triple-expansion steam engines
that produced 5,500 horsepower.
Maximum Speed: 20 knots
Cruising range: more than 5,000 miles at 12 knots
The initial actions of German submarines were mostly individual,
they acted on their own.
But when convoy protection was reinforced,
when the Allies constructed many special ships to escort transports,
the Germans had to invent a way to overcome their defenses.
That's when they devised the so-called "wolf pack" tactic.
It worked like this: a U-boat discovers a convoy.
The flagship that commands a "wolf pack" or a system of "wolf packs"
transmits the order to other U-boats to move to that area.
And those U-boats start to gather to intercept the convoy. Lots of them.
Diamantina was fitted with a type 271 radar,
which actually played a pivotal role in changing the course of WWII.
The Britons had developed what was known as the greatest secret of WWII,
which was the cavity magnetron,
and the cavity magnetron is at the heart of this type 271 radar.
Its major role in the protection of convoys
was its ability at night to detect submarines on the surface
as they approached the convoy to attack the convoy.
And the Germans were unaware that the escorts were fitted with radar
and were able to see or detect these submarines
as they were making their approach to make their attack.
The radar could only detect a submarine if it was on the surface,
but they usually surfaced just prior to an attack.
Unfortunately, warships in World War II were unable to detect torpedoes
that had been fired,
and they relied entirely on lookouts,
picking up the track of the torpedo as it approached the ships.
And because of the propulsion system used by most of the torpedoes,
they could see a line of bubbles coming to the surface.
Well, I can only relate a training experience,
when Murchison was exercising with British submarines.
And I was given the task of looking for torpedo bubbles.
But when I saw the bubbles, by the time I reported them to the captain,
the bubbles were now on the other side of the ship,
so his words to me were: “Signalman, if this was a real war situation,
we would be now manning the lifeboats.”
Even if a ship managed to dodge torpedoes thanks to the vigilance of signalmen,
it was difficult to retaliate, because the submarines
swiftly disappeared from sight.
Having launched torpedoes, submarines dived
and they could only be discovered with the help of a special device—sonar.
Near the bow of the ship just close behind us here is a black dome,
and that is the sonar dome fitted to the ships.
And a sonar is a bit like a torch beam which is projecting a sound signal
out into the water and hoping to get a reflection back
off something like a submarine.
And that sonar equipment is directional, so where it’s pointing, where it’s looking,
where it’s sending the beam out, is under the control of the operator.
And that was one of the vital sensors that these ships had for detecting submarines.
A frigate's captain had to deal with the shortcoming of sonar
when planning a counter-attack against a submarine;
it lost contact with the target at a distance of about 140 meters.
Thus, the captain had to guess the possible course of the submarine
and direct his ship straight towards it.
Under the conditions of an intense battle,
decisions had to be made in mere seconds,
and controlling the maneuverable frigate required some skill, especially in rough seas.
One of the interesting things about here
is that the helmsman who was steering the ship
is actually unable to see where we are going.
And that’s fairly typical of British warships of the Second World War.
Orders come down to the helmsman from the bridge deck above us,
where the captain, or the officer of the watch,
is actually giving instructions for steering the ship.
And also for giving the engine orders here through the telegraph,
which then go down to the engine room to change the ship’s speed.
I’m seated in the captain’s day cabin aboard the frigate Diamantina.
And these ships were very unique
because they incorporated a major design feature that brought the whole ships company
into the middle section of the ship close to where we are now.
However, when the Battle of the Atlantic started,
and the destroyers were operating
in the very rough conditions in the North Atlantic,
the British Navy was losing officers swept over the side
when they were moving from their accommodation in the after section of the ship
to try to get to the bridge across the upper decks.
There was no way through the engineering spaces
to get to the forepart of the ship.
So, when they came to the design of these ships,
the British realized that they needed to move the officers
into the forward section of the ship, which is where we are today.
At the end of April 1943, after a week's storm-filled cruise,
convoy ONS-5 was intercepted by a “wolf pack.”
The convoy's screening ships, including several River-class frigates,
repelled the attacks of about 40 submarines for several days.
Thirteen transports were sunk.
The German submarines had the advantage until the fifth day of battle,
when the convoy entered a stripe of dense fog.
In a single moment, hunters became prey,
betrayed by the bright markings on radar screens of escorting ships.
In the impenetrable haze, the British frigates competently found German U-boats
and attacked them.
For combat against a submerged submarine,
the ship carried over 100 depth charges in its depth charge magazine,
and these were large cylinders full of explosives
that would either roll off the stern
or launch out from the side of the ship in a pattern set at different depths
to try to explode around the submarine and close to the submarine,
and either to crush the submarine or force the submarine back to the surface.
There were two ways to drop depth charges on River-class frigates.
From rails on the aft and with the help of K-gun throwers
installed on the ship's sides.
The simultaneous use of these two methods
increased the effective area and probability of damaging a submarine.
The Hedgehog mortar launcher was another anti-submarine weapon of the River class.
It fired 24 30-kilogram bombs ahead of a ship.
A salvo from a Hedgehog covered an area of more than 30 meters in diameter.
The system was effective, but unreliable at first,
that's why depth charges remained the primary
anti-submarine weapon of River-class frigates.
However, escorting ships had to engage submarines
in artillery duels quite often as well.
These 4-inch guns on Diamantina were all mechanically operated.
So, they had men manning the elevation and men manning the training of the weapon,
and there were no inputs from other sources
such as a gun director which you would find on larger warships.
So, these were all in local control.
They would target and engage the enemy unit from this weapon,
under verbal direction from the gunnery officer who was on the bridge.
At the time when, in the northern hemisphere,
the grandiose battle for the Atlantic reached its turning point,
Walkers Limited shipyard in Maryborough, Australia, laid down frigate HMAS Diamantina.
By the moment of her launch, the Atlantic was basically clear of German submarines,
thanks in no small part to British River-class frigates.
Now, their Australian sister-in-arms was to participate
in the final act of World War II.
The frigate was commissioned in April 1945.
Diamantina took part in operations against Japanese troops in New Guinea,
near Solomon Islands, and Bougainville Island.
Diamantina has, in my mind, three claims to fame.
First of all, she was the last Australian warship
to fire a shot at the Japanese in WWII.
Her second claim to fame was that the Japanese garrison
at the Island of Nauru, an ocean island in the Pacific,
actually surrendered on the quarterdeck of this ship.
And the third claim is that she’s the last in the world of this class of ship.
After World War II, River-class frigates continued to serve
in the navies of 20 countries for several decades.
In 1959, Diamantina was re-equipped as an oceanographic survey ship.
Her contribution to the study of ocean depths was acknowledged
when a fracture zone in the Indian Ocean was named after her.
In the 1980s, the ship was honorably decommissioned
and placed in a comfortable dry dock at Queensland Maritime Museum in Brisbane.
Now, the bright Australian sun warms the deck of the last ship from the River class—
a family of small ships that struck terror
into German "wolf packs" in the Northern Atlantic.