Missing Pieces: - Royal Australian Navy

112 Missing Pieces
a good idea of their enemy’s presence and operating areas. However, transmissions
were not always detected, intercepts not always decrypted in time for a counter-attack,
the quality of DF fixes varied widely, and imperfections in the command, control and
communications system were soon revealed. 318
Another source of analysed intelligence came from the Admiralty, in the continuous
stream of tactical lessons from the Battle of the Atlantic. These were either promulgated
directly to SWPA units or in ‘A/S [antisubmarine] School Confidential Instructions’,
which were issued to RAN ships from February 1941. 319 Later they were incorporated in
GHQ Standard Operating Procedures (SOPs). As well, RAN ships had the benefit of WIR
(discussed in Chapter 1) and the Admiralty publications CB3043, Defence of Merchant
Shipping, and CB3044, Manual of Anti-submarine Warfare. From 1943, CSWPSF staff
and NOICs used the British-United States Routing Agreement to defensively route
merchant shipping to bypass enemy submarine concentrations.
The initial stages of the campaign began slowly. The IJN, lacking any other effective form
of intelligence-gathering on its new target area, despatched I-25 on a reconnaissance
patrol through the Coral Sea, down the east coast of the Australian mainland, around
Tasmania and thence to the North Island of New Zealand in February—March 1942. 320
This was in preparation for the midget submarine campaign, involving five large
submarines and three midgets, which culminated in the unsuccessful attack on
Sydney Harbour on the night of 31 May—1 June. The first blows were struck by I-21,
with the sinking of two merchant ships off New Caledonia on 5 and 7 May, followed
by an attack by I-19 on a ship off Newcastle on 16 May. However, it was not until after
the Sydney attack, and six subsequent attacks on shipping in the vicinity of Sydney,
that CSWPSF suspended sailings and instituted a convoy system off the east coast on
4 June. There is no intelligence explanation for this delay in responding to evidence.
By 30 May CANF and CSWPSF had the evidence of the attack of 16 May, DF fixes on
submarines in the vicinity of Sydney, Sigint confirmation of IJN submarine interest
in Sydney, and the presence of aircraft-carrying boats in the area on which to base
their appreciations. 321
Despite a continuing stream of intelligence and DF reports on some of the IJN
submarines lingering in the Sydney area, there were no successful engagements,
although at the time claims of up to ‘six or seven’ submarines destroyed were made. 322
These were subsequently disproved by Sigint decryptions from the ‘victims’. The failure
to intercept, let alone attack and sink, any of the five large submarines which had been
loitering near Australia’s largest naval base for between six and nine days, and one of
which shelled Sydney and Newcastle on the night of 8 June, is an accurate reflection
of the ASW capabilities of the RAN and RAAF, and of the system which directed their
operations at the time.
After a successful attack on a convoy straggler north of Sydney on 12 June, the Japanese
flotilla retired and, after six weeks of ASW inactivity, CSWPSF ceased convoy operations