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Underwater archaeologists have settle the wrecks of three military ship involved in Japan ’s invasion of Alaska ’s distant Aleutian Islands in World War II — an almost - drop conflict sometimes yell the " forgotten struggle " by historians .
The wrecks of the vessels — two Nipponese freighters and the American cable ship SS Dellwood , which position undersea cable’s length during the state of war — were break last month during an sashay to Attu Island , at the westernmost tip of the Aleutians .
The advanced sonar system uses new hardware and advanced software to create scans of the seafloor at greater distances and higher resolutions than earlier systems, including this scan of the Kotohira Maru wreck.
The Nipponese ships were sunk by bomb from American aircraft after Japanese troops intrude on the island in June 1942 , roughly six calendar month after theattack on Pearl Harbor , and the American ship sank about a calendar month after the Nipponese encroachment had been defeated almost a yr later , during efforts to reenforce the island ’s defenses .
" The original [ Nipponese ] idea was to turn Attu into an ' unsinkable aircraft mailman ' " for attacks on other American locations , maritime archeologist and task cobalt - leaderDominic Bushtold Live Science .
" But as thing started to deepen in the Pacific , they were abandoned by the purple instruction and basically told to hold out for as long as they could — basically , to die with pureness , " added Bush , who was a doctorial student at East Carolina University ( ECU ) at the sentence of the expedition and is now a investigator for the archaeological nonprofitShips of Discovery .
A winch on the wreck on the S.S. Dellwood, which sank while laying cables for a new American airbase on Attu built after the Japanese invasion was defeated in May 1943.(Image credit: World Scanning Project)
Related:30 incredible sunken wrecks from WWI and WWII
Battle of Attu
Attu and the nearby Aleutian island of Kiska were the only parts of North America invaded and occupied by a foreign enemy during World War II , although Nipponese warplanes also bombed other Aleutian island . In response , the United States spend rough a class bombing the Japanese there with warplane and , finally , drove out the Japanese with a force ofalmost 35,000 American and Canadian soldier .
The final stages of the encroachment admit theBattle of Attu , which claimed the life of 2,351 Japanese and 549 Allied scout group in May 1943 .
Bush and his colleagues at ECU — including the project ’s conscientious objector - leader , maritime archaeologist and historianJason Raupp — had spend years researching the Aleutian Island wreck and were able-bodied to locate all three during a two - week sashay in July .
Part of the hull of the Japanese freighter Kotohira Maru, which was carrying supplies to the Japanese invasion forces on Attu in January 1943 when it was sunk by bombs from a U.S. warplane.(Image credit: World Scanning Project)
The researchers teamed up with several strategic mate , including the JapaneseWorld Scan Project , which scans environmental and archaeological site with drones and other automaton , to find out as much as they could about the wrecks .
" Nobody had documented these wrecks before , " Raupp told Live Science . " So we went out there and searched … and since we had about four years of research and preparation , it made the recognition sluttish when we discover them . "
Advanced sonar
The wreck huntsman searched the domain on board a former crab - fishing vessel — the Norseman II — which has been commute into a scientific research ship and is equipped with a remotely operated underwater fomite that took telecasting of the sunken ship . The wreck were located by a sonar regalia towed behind the research ship ; the regalia hold equipment for an modern type of echo sounder called " synthetic aperture " echo sounder , which uses the reflections of sound pulses to situate objects underwater .
Raupp explain that the system combines fresh computer hardware and modern computer software processing technique to create three - dimensional scans of the seafloor over much corking aloofness and with much higher solving than earlier sonar systems .
" It allows for increase efficiency of a survey , because you are capable to cut across monolithic swaths of the seabed with a high level of resolution , " he enjoin . " We would have needed weeks to accomplish the same result using standard sonar . "
The researchers used advanced “synthetic aperture” sonar to locate the wrecks on the seafloor, including the wreck of S.S. Dellwood beneath roughly 300 feet of seawater.(Image credit: ThayerMahan, Inc.)
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The advanced sonar system uses new hardware and advanced software to create scans of the seafloor at greater distances and higher resolutions than earlier systems, including this scan of the Kotohira Maru wreck.(Image credit: ThayerMahan, Inc.)
The wreck of the Dellwood and one of the Japanese freighters , Kotohira Maru , were locate offshore at a deepness of about 300 feet ( 90 meters ) , and the wreck of the other Japanese merchant ship , Cheribon Maru , was found in shallow water near the shoring .
Bush enjoin the damage observed on the shipwreck of the two Japanese bottom reassert reports of their sinkings by bomb calorimeter from American warplanes .
The recessed American ship had been laying cable for a new air basis built there after the invasion when it struck an chartless underwater pinnacle , Bush say , and the researchers had also find grounds that anti - undersea meshwork were used to defend Attu ’s main porthole from attacks by Japanese Italian sandwich .
The researchers conducted a two-week expedition to Attu in July this year on board the Norseman II, a former crab fishing boat that has been converted into a scientific research ship.(Image credit: Support Vessels of Alaska, Inc.)
The research ship is equipped with a “katfish” remotely-operated underwater vehicle (ROV) that the researchers used to make videos of the sunken wrecks.(Image credit: Phil Hartmeyer)
Data from the advanced “synthetic aperture” sonar equipment towed behind the ship was processed on board, to allow the researchers to quickly locate the wrecks on the seafloor.(Image credit: Sean Mack)
