An Cosantóir

An Cosantóir Dec 2016 / Jan 2017 www.dfmagazine.ie 36 | By JAMES SCANNELL Submarine involvement at Pearl harbour I n october 1941 as Japanese military planners finalised the de- tails of their attack on the US Pacific Fleet at the Pearl harbour naval base in hawaii, using aircraft launched from aircraft carri- ers, one minor addition was made; the deployment of five midget submarines to attack between the first and second airstrikes. The Imperial Japanese Navy's two-man, Type A, midget submarine, which entered service in November 1940, was 23.9m long, 1.8m wide, and 3m high. Its 600hp electric motor gave it a 23kt surface speed (19kt submerged). It had a range of 33km, a diving depth of 30m, and was armed with two 17.7-inch torpedoes in individual tubes. In August 1941 submariners came up with the concept of using them to penetrate enemy naval bases to attack their ships. They proposed that, due to their limited operation range, they could be carried to their target area by larger submarines acting as mother ships and then released to carry out their missions. Feasibility studies on attacks against naval bases at Pearl Harbour, San Francisco, Hong Kong, Singapore, and Sydney, were followed up by a series of night exercises in Hitajo Bay, which, un- known to the crews, resembled Pearl Harbour. In October the planners of the Pearl Harbour attack decided to include five midget submarines, which would be transported to the target area by five Type C-1 submarines. The midget submarines were fitted with net cutters and propeller guards, and 140kg scut- tling charges, as their crews were under orders not to allow them fall into enemy hands. In November three Japanese officers travelled to Pearl Harbour where they spent four days on a reconnaissance operation before returning to Japan where the plan for the attack on Sunday Decem- ber 7th was finalised: • In Washington DC, two hours before the attack, the Japa- nese ambassador would present a diplomatic note to the US Secretary of State severing diplomatic relations. (Due to a delay in typing up the formal note, it was not delivered until the attack was in progress.) • At 8am in Hawaii the first wave of carrier-borne aircraft would commence their attack on the Pacific Fleet at anchor in Pearl Harbour and the surrounding infrastructure. • The midget submarines would enter the harbour and com- mence their attacks after the departure of the first wave of aircraft and before the arrival of the second wave. On November 27th the Japanese strike force of six aircraft carriers, two battleships, two heavy cruisers, one light cruiser, nine destroyers, three submarines, and eight tankers, set sail in great secrecy from Tankan Bay, Japan, maintaining strict radio silence. Proceeding separately to Pearl Harbour were the five midget submarines carried on their mother ships. On December 2nd the striking force received the coded mes- sage 'Climb Mount Niiaka!' confirming that the attack on Pearl Harbour was to proceed. In the early hours of December 7th the midget submarines, M-16, M-22, M-18, M-20, and HA-19, were launched from their mother ships, starting their approach to Pearl Harbour under orders not to commence their attack before 8am. At 3.42am the mine-sweeper USS Condor spotted what they took to be a submarine periscope that changed direction as they ap- proached. At 3.58am she signalled the destroyer USS Ward: 'Sighted, submerged submarine on westerly course, speed nine knots.' USS Ward went to battle stations but, despite an extensive search using lookouts and sonar, found no trace of the submarine, so the crew stood down at 4.43am. Battleship Row with torpedo tracks leading to USS West Virginia and USS Oklahoma

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