Remote-Sensing Survey of D-Day Landing Sites (Normandy, France)
On June 6, 1944 an expeditionary force comprised of soldiers from the United States, Great Britain, Canada, Poland, Norway, and other nations, including members of the French Resistance, crossed the English Channel for the Allied invasion of Normandy. Within 24 hours, over 5,000 vessels transported 175,000 Allied troops and their equipment, including 50,000 vehicles of all types, across 60 to 100 miles (96.56-160.9 kilometers) of open water to assault a well-fortified German beachhead. Dubbed Operation Overlord, the waterborne assault was described by British Prime Minister Winston Churchill as the most difficult and complicated operation of its kind to ever take place. At the close of D-Day, the allied invasion front stretched across more than 55.92 miles (90 kilometers) of beachhead. The Atlantic Wall, which took the Germans four years to construct and absorbed a large percentage of German materiel and labor, fell in just one day. However, Allied penetration of the Atlantic Wall came at a costly price, resulting in nearly 5,000 casualties. By D-Day plus one, the wreckage of landing craft and motorized vehicles were spread across the invasion beachheads to such an extent that landing operations were suspended.
In 2000 the Naval History & Heritage Command's Underwater Archaeology Branch began a three-year archaeological remote-sensing survey to locate and document U.S. Navy losses incurred during the D-Day invasion. The remnants of historic craft located off the allied landing sectors represents a microcosm of World War II-era U.S. Navy shipwrecks and submerged battlefields worldwide, as well as the largest known assemblage of naval-related vessel losses anywhere in the world. The project was initiated in large part to develop a criteria or template for the scientific archaeological assessment and preservation of a significant historical resource base. Data gathered during the survey also represented a fundamental function of the Underwater Achaeology Branch: to identify, locate, evaluate, nominate, and protect historically significant submerged U.S. Navy properties.
The project area included offshore segments of the American landing sectors--designated Utah Beach, Point du Hoc, and Omaha Beach--along a 20-mile stretch of the Normandy coastline. To assist in the discovery and interpretation of American naval losses during the D-Day assault, the Service Hydrographique et Oceanographique de la Marine (SHOM) provided the U.S. Navy a database of all current wreck and obstruction chartings for the Baie de Seine. The Underwater Achaeology Branch employed an array of remote-sensing equipment during the survey, including a magnetometer, side-scan sonar, remotely operated vehicles (ROVs), and a multibeam echo-sounding system (MBES).
The Naval Surface Warfare Center, Carderock (NSWCC) supplied the project with a Deep Ocean Engineering Phantom III S2 vehicle, which served as a remotely operated work platform to collect digital still images and streaming video of selected targets and features. During the 2001 and 2002 field seasons, ROVs collected approximately 110 hours of quality video and permitted project archaeologists to maintain complete and real-time quality control over the data collection process. MBES operations were also quite successful; the near field beam-forming capability of the RESON 8125, combined with 3-D visualization techniques, provided an unprecedented level of detail to the survey data. In many instances, project archaeologists were able to recognize individual components of a particular wreck (ramps, gun turrets, hatches, etc.), its state of preservation, and impact on the surrounding seafloor.
During the 2002 field season, the Underwater Achaeology Branch marked a project milestone by completing remote-sensing operations at Banc du Cardonnet (906 hectares/3.498 square miles), Utah Beach (1,206 hectares/4.656 square miles), Pointe du Hoc (384.7 hectares/1.485 square miles), and Omaha Beach (2,226 hectares/8.595 square miles). The Banc du Cardonnet survey grid contained the charted remains of LCT-777, LCT-244, LCT-305, LCI-232, PC-1261, a possible Sherman tank, three possible vehicles (e.g., a possible U.S. Army DUKW), one barge, USS Meredith (DD-726), LST-523, HMS Minster, 10 uncharted and undetermined wreck sites and USS Rich (DE-695). Of these, the Underwater Achaeology Branch positively identified only Meredith and Minster. Archival research and oral history interviews provide compelling evidence that the identities of LST-523 and LST-496 have been confused with one another. Moreover, contemporary photographs and salvage reports indicate that LCT-777 and LCT-305 are not on the Banc du Cardonnet, as currently charted.
The Utah Beach survey grid contained the charted remains of two unidentified barges, three unidentified wrecks, one liberty ship, SS Charles Morgan, HM LCT-524 and USS Tide. In addition to charted wrecks, the survey revealed an unidentified landing craft lying adjacent to the charted liberty ship. Despite collecting a significant amount of field data and archival material, the Underwater Achaeology Branch was unable to positively identify the liberty ship, the landing craft adjacent to it, or the two barges. However, archival data did reveal considerably discrepancy between the charted and actual locations of the SS Charles Morgan.
Survey efforts within the Pointe du Hoc grid focused on an uncharted and unidentified wreck that was first investigated by the Underwater Achaeology Branch in 2001. The wreck rests on a rock reef approximately one kilometer NNW of Pointe du Hoc. Sonar data indicated that it measures approximately 13 meters in length, is 5 meters wide, rises approximately one meter above the seabed, and is about 334 meters SE of a landing pontoon charted by SHOM. It also appears to be associated with four other unidentified targets. These targets are clustered as two distinct pairs only 8 meters apart. Although the Underwater Achaeology Branch collected additional side-scan and multibeam sonar data at the wreck site in 2002, it still could not be identified due to a lack of sufficient diagnostic features.
The Omaha Beach survey grid contained numerous charted and uncharted wrecks and obstructions. Charted wrecks included the USS Partridge (ATO-138), USS Susan B. Anthony (AP-72) and caissons and block ships associated with the Mulberry Group of Saint-Laurent-sur-Mer. In addition to investigating known wreck sites, the Underwater Achaeology Branch discovered at least five unidentified craft and collected multibeam and sonar data within the Omaha Beach survey sector that verified the remains of two M4A2 Sherman tanks and two other tracked vehicles. The Underwater Achaeology Branch also surveyed an area near Pointe et Raz de la Percee to locate and examine an unidentified LST charted by SHOM. The exposed component of this wreck comprised a section of hull measuring approximately 25.7 meters in length, 9.27 meters in beam, and rising to a height of 1.6 to 2.5 meters above the seabed. Although originally labeled by SHOM as the remains of an unidentified LST, the craft's beam dimensions measure about 6.1 meters narrower than an LST class craft. In addition, its two GM 6-71 engines are much smaller than the 12-cylinder GM 12-567 engines that powered World War II-era LSTs.
The Underwater Achaeology Branch's three-year archaeological remote-sensing survey to locate and document U.S. Navy D-Day losses concluded in the summer of 2002. The project has now entered a new phase of intensive archival research and the collection of oral histories from D-Day participants. The majority of archival material was collected from the National Archives and Records Administration and comprises cartographic material (such as Bigot Maps), textual records (i.e., war diaries, action reports, deck logs) and combat-related photographic documents (both still photographs and movie film footage).
While comparative imagery analysis provided cursory identification of vessel types, it will take a great deal of archival research to sift through the scant historical data and present positive identifications for the wreck sites detected during the remote-sensing phase. Data integration and Geographical Information Systems products allow the implementation of spatial analyses techniques, which will be particularly useful in visualizing, among other things, operational-level battlefield tactics during the Normandy invasion.