Your Turn: ThayerMahan helps uncover WWII vessels sunk in U.S. waters

The Groton defense and offshore wind contractor ThayerMahan, which creates vessels and listening devices that help the Navy with maritime surveillance, has announced that one of its advanced devices was used to discover Japanese and American vessels that were sunk off the Aleutian island of Attu during the only naval conflict after the attack on Pearl Harbor to occur in U.S. waters.The research provided the first underwater archaeological survey around Attu and marks the beginning of what is sure to be an increased focus on the nearly forgotten campaign and by extension Alaska's World War II history. The Battle of Attu is also known as the "Forgotten Battle" because it was eclipsed by larger campaigns in the Pacific Theater.ThayerMahan provided its advanced synthetic aperture sonar to the research team that discovered the World War II relics. The foreign vessels are the only Japanese military ships believed to be situated within U.S. state waters. Using ThayerMahan's cutting-edge survey technology, the team of archaeologists, hydrographers, and robotic engineers located three World War II-era shipwrecks. ThayerMahan's high-resolution sonar also enabled the identification of many smaller targets, most of which would be impossible to see using more traditional forms of remote sensing.The seafloor around Attu is littered with vestiges of World War II, including dozens of anchors, chains, mooring blocks, and sunken buoys, as well as examples of materials used in base construction, such as timbers, piping, and cable. Perhaps most interesting was the numerous sections of anti-submarine netting that could be clearly discerned. With the centimeter resolution offered by synthetic aperture sonar, the interconnected metal rings of these nets, reminiscent of chainmail armor, were documented in stunning detail. The ThayerMahan technology was used in tandem with a newly developed camera system for remotely operated vehicles provided by World Scan Project.Though fighting on the Aleutian Island was limited to three weeks in May 1943, Attu had been the site of significant military activity ever since its invasion by the Japanese military on June 7, 1942. That offensive marked the first time a foreign power occupied U.S. territory in North America since the War of 1812 – a feat that has not since been repeated. Following the liberation of the remote island by American forces, it was transformed into a military outpost that operated throughout the war's duration.The first vessel located was the Kotohira Maru, a 5,000-ton freighter that carried provisions, housing materials, and fuel for Japanese troops stationed on Attu. It was sunk by a U.S. Navy weather plane on January 5, 1943, with only two of its crew rescued. Despite war-era charts indicating its suspected location, the survey team located the fairly intact remains of Kotohira Maru over a kilometer from its last reported position, in nearly 300 feet of water.Closer to shore, Yasumasa Ichikawa, chief technical officer of World Scan Project, utilized a combination of aerial and underwater drones to inspect the purported location of the second Japanese shipwreck, Cheribon Maru. Draped in kelp and other marine growth, the remains of the 3,000-ton freighter, sunk on Thanksgiving Day 1942 by American bombers, were observed in less than 30 feet of water. At least 15 crew members perished during the sinking, with some estimates as high as 55.The lone American ship located was the U.S. Army cable layer SS Dellwood, whose discovery came 81 years to the day of its sinking. The nearly 3,500-ton ship had struck a submerged pinnacle on July 19, 1943, and sank while being towed to a nearby dock. Both sonar and ROV imagery revealed the severely compromised state of the former cable ship, likely the result of post-wrecking bombing as it had become a navigational hazard. Now resting over 100 feet below the sea surface, SS Dellwood provides a unique glimpse into U.S. military operations in the Aleutians after the battle.The July project, titled "Exploring Attu's Underwater Battlefield and Offshore Environment," was led by Dominic Bush, research associate with Ships of Discovery, Inc.; Jason Raupp, assistant professor of maritime studies in East Carolina University's Department of History, and Caroline Funk, assistant research professor at University of Buffalo.The project was funded through complementary grants from NOAA Ocean Exploration and the U.S. National Park Service American Battlefield Protections Program.For information, the researchers can be contacted at rauppj14@ecu.edu, Dbush@alumni.nd.edu or cfunk@buffalo.edu.Information is this story was provided by ThayerMahan. To submit stories to the Times, email times@theday.com.