Missing Pieces: - Royal Australian Navy

Taking The OFFensiVe 1942–45
to prevent landings by positioning underwater obstructions also had to be identified
and marked for removal prior to the landing. In most cases, these operations had to
be conducted in sight of an enemy-held coast, and with the constant threat of air and
coastal battery attack on the surveying vessels. 352
Extensive use was made of the photo-reconnaissance technique pioneered by the RAN
Hydrographic Department. While photographic interpretation could provide accurate
landform information and an indication of the extent of shallows and hazards in waters
close to the beach, the technique was ineffective in waters deeper than a few metres
and could not provide accurate information on the nature of the beach itself. Deeper
waters had to be surveyed, while a personal inspection of the beaches to provide
gradients, firm going for vehicles and machines, and debouchments from the beach
was normally required. 353 As the war progressed, aerial photography was steadily
supplemented by periscope photography from submarines, while AIB was tasked to
make the physical inspections in advance of landings.
Accordingly, the survey and hydrographic force became an integral part of amphibious
operations as the war progressed. This required more ships than the Hydrographic
Branch possessed, even though it had acquired a number of small civilian craft to
augment its capabilities inshore, so the decision was taken to equip some of the
Australian Corvettes (AMS) for surveying duties. This was a significant indication of
the importance the Allies attached to the hydrographic effort when, as described in
the previous section, CSWPSF was crying out for escorts for ASW duties. There were
several advantages to this approach, not least that the ships were armed and could
provide an element of self-defence; another was that the corvettes were sonar-fitted.
Using this sensor, and with their Oropesa mine sweeps set for a minimum depth,
check sweeps could be carried out rapidly along routes scheduled to be used for the
approaches to an amphibious objective. The first such deployment by HMAS Whyalla,
in January 1943, fully opened the route from Milne Bay to Oro Bay, thus assisting in
the capture of Buna the following month. 354
On 21 June 1943, the seven RAN survey ships were formed into TG 70.5 to undertake
the task of surveying and charting operations for the US 7th Fleet in the SWPA. The
Officer Commanding RAN Hydrographic Branch became Commander Task Group (CTG),
and was appointed Charting Authority for Allied Naval Forces SWPA. The task group
was soon to be joined by 11 USN ships, but the CTG remained an Australian. In the
same month, two new AMS specially configured for hydrographic work, HMAS Ships
Shepparton and Benalla, surveyed a route for the landing on Kiriwina Island, the first
pre-assault survey in the SWPA. This unopposed landing was used to test theories and
to identify areas requiring attention. One such lesson was the need for survey vessels to
pilot amphibious forces to their beaches because of ‘the meagre navigational facilities
of the amphibious craft, the inexperience of the personnel and the incomplete surveys
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