The first half of 1944 saw another increase in patrols, number of ships and tonnage sunk, despite the fact that March, because of the fears of attack, saw only tow patrols go out.
The number of submarine patrols from Fremantle was increased to an average of nine and 75 enemy ships were sunk in the period, with a tonnage of almost 320,000.
April 1944 saw the best monthly total so far, accounting for almost a third of the six month total.

After no submarine losses from Fremantle for almost a year, July and August saw the loss of three submarines in quick succession, USS Robalo (SS-273), USS Flier (SS-250) and USS Harder (SS-257).
Harder was lost without survivors while four of the crew of Robalo may have survived the initial sinking, but not captivity.
Of the crew of Flier, at least thirteen survived the initial sinking but only eight of those made it ashore.
Uniquely, these eight were rescued and returned to Australia without ever falling into Japanese hands, being helped by Filipino Guerilla fighters and picked up by another US submarine.

The second half of 1944 saw the arrival of British submarines at Fremantle, which previously had been engaged in the Mediterranean, then moved to Ceylon and, finally, to Western Australia.
The first to arrive was the HMS Porpoise, on 10 August, followed by the depot ship HMS Maidstone in early September while the eleven submarines attached to the ship first carried out patrols in the Strait of Malacca before arriving at Fremantle as well.
It was the first time that Royal Navy ships were based in Western Australia, with the contingent also including two Dutch submarines.
While the new base was very popular with the British submariners, offering superior opportunities for recreation between patrols, in comparison to Ceylon, the remote location meant the submarine patrols were longer than the previous short ones from the island.
With 52 days on one patrol from Fremantle, HMS Tantalus set a new record for the longest patrol of a British submarine during the war so far from October to December 1944.

British submarines, smaller than their American counterparts, were predominantly used in shallower water, and against smaller crafts, which they attacked with their deck gun rather than torpedos.
This approach carried a number of risks, it being harder for a submarine to hide in shallow water and the gun crew being exposed to enemy defensive fire.

British submarines based in Fremantle were also heavily involved in special operations.
Porpoise became the first British submarine to go on patrol from Fremantle in September 1944 and was selected, because of its size, to carry Western Australia-trained members of the Z Special Unit on the unsuccessful Operation Rimau.

The second half of 1944 proved to be the pinnacle of the war efforts of the US submariners based in Fremantle.
In 83 patrols, the boats sank 105 enemy ships at a combined tonnage of 445,000.
Admiral Christie, in charge of the Fremantle submarines since 1943 and overall commander of all US submarines in Australia for a brief period in November and December 1944, was informed of his upcoming replacement soon after.
Christie was most likely replaced because of his insistence of having the late Samuel David Dealey, commander of the Harder, decorated with the Medal of Honor, something he did succeed in once back in the US.
His replacement, Rear Admiral James Fife, took over on Christmas Day 1944.
The first half of 1944 saw another increase in patrols, number of ships and tonnage sunk, despite the fact that March, because of the fears of attack, saw only tow patrols go out. The number of submarine patrols from Fremantle was increased to an average of nine and 75 enemy ships were sunk in the period, with a tonnage of almost 320,000. April 1944 saw the best monthly total so far, accounting for almost a third of the six month total.
After no submarine losses from Fremantle for almost a year, July and August saw the loss of three submarines in quick succession, USS Robalo (SS-273), USS Flier (SS-250) and USS Harder (SS-257). Harder was lost without survivors while four of the crew of Robalo may have survived the initial sinking, but not captivity. Of the crew of Flier, at least thirteen survived the initial sinking but only eight of those made it ashore. Uniquely, these eight were rescued and returned to Australia without ever falling into Japanese hands, being helped by Filipino Guerilla fighters and picked up by another US submarine.
The second half of 1944 saw the arrival of British submarines at Fremantle, which previously had been engaged in the Mediterranean, then moved to Ceylon and, finally, to Western Australia. The first to arrive was the HMS Porpoise, on 10 August, followed by the depot ship HMS Maidstone in early September while the eleven submarines attached to the ship first carried out patrols in the Strait of Malacca before arriving at Fremantle as well. It was the first time that Royal Navy ships were based in Western Australia, with the contingent also including two Dutch submarines. While the new base was very popular with the British submariners, offering superior opportunities for recreation between patrols, in comparison to Ceylon, the remote location meant the submarine patrols were longer than the previous short ones from the island. With 52 days on one patrol from Fremantle, HMS Tantalus set a new record for the longest patrol of a British submarine during the war so far from October to December 1944.
British submarines, smaller than their American counterparts, were predominantly used in shallower water, and against smaller crafts, which they attacked with their deck gun rather than torpedos. This approach carried a number of risks, it being harder for a submarine to hide in shallow water and the gun crew being exposed to enemy defensive fire. 
British submarines based in Fremantle were also heavily involved in special operations. Porpoise became the first British submarine to go on patrol from Fremantle in September 1944 and was selected, because of its size, to carry Western Australia-trained members of the Z Special Unit on the unsuccessful Operation Rimau.
The second half of 1944 proved to be the pinnacle of the war efforts of the US submariners based in Fremantle. In 83 patrols, the boats sank 105 enemy ships at a combined tonnage of 445,000. Admiral Christie, in charge of the Fremantle submarines since 1943 and overall commander of all US submarines in Australia for a brief period in November and December 1944, was informed of his upcoming replacement soon after. Christie was most likely replaced because of his insistence of having the late Samuel David Dealey, commander of the Harder, decorated with the Medal of Honor, something he did succeed in once back in the US. His replacement, Rear Admiral James Fife, took over on Christmas Day 1944.
Fremantle submarine base