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Immediate Pre-Invasion Top Secret Map of the German Defenses Between Omaha and Utah Beaches.

This "Defences" overprint map of Isigny, France (between Omaha and Utah beaches), updated in May 1944 to include Top Secret defense information, delineates the strategic area around Isigny-sur-Mer, France, at an impressive scale of 1:12,500. Prepared for the imminent Allied invasion of Normandy during World War II, it highlights key military defenses, infrastructure, and geographical features with precise detail, aimed at briefing ground troops and facilitating operational planning.

The map focuses on the area surrounding the mouth of the Vire River and the Baie des Veys, just to the west of Omaha Beach. This area was heavily fortified, and the map reflects careful reconnaissance efforts to identify German defensive positions, including gun emplacements, strongpoints, and fortified houses. Symbols on the map, explained in a detailed legend on the verso, indicate both confirmed and unconfirmed defense features such as anti-tank ditches, minefields, roadblocks, and wire obstacles, essential intelligence for the assault troops.

The landscape around Isigny is shown with notable specificity, including the positions of drainage ditches, dykes, and marshlands. These features, which could impede movement, were important for planning as they shaped the routes available to advancing troops. The map includes notes on the presence of sandbanks and mud flats in the Baie des Veys, warning that these could vary with tidal changes and might present additional hazards during the initial landings.

In addition to detailing natural features, the map highlights infrastructure critical to the advance inland. Roads are classified by type and width, with bridges and key junctions marked. The town of Isigny-sur-Mer itself is shown with significant detail, including areas marked as subject to “heavy flak fire,” indicating known German anti-aircraft defenses. The mapping of hedges, trees, and cleared fields further reflects the level of detail needed for close-quarters combat and tactical movements.

Compiled from aerial photography and French survey data, the map was part of the enormous planning that underpinned the D-Day operations. With its annotations in purple and blue, and the classified defense legend on the reverse, this map reflects the complexity and precision of Allied preparations. This map was intended for the highest levels of operational planning, and its detailed portrayal of the Isigny area was crucial in enabling Allied forces to overcome German defenses and secure a foothold in Normandy.

Isigny

Isigny-sur-Mer, a small town in the Normandy region of France, played a significant role in the events of D-Day, June 6, 1944, during World War II. Situated between Omaha and Utah, two of the five Allied landing beaches, Isigny became a crucial junction for connecting the American forces landing at these sites. Its strategic position made it an important objective for the Allies, who needed to secure a continuous front and establish a supply line between the two beachheads. Despite being heavily bombarded during the invasion, resulting in significant destruction, the capture of Isigny was vital for the success of the overall Normandy Campaign. It facilitated the movement of troops and material and helped in establishing a foothold in Nazi-occupied France, contributing to the eventual liberation of Europe from Axis powers.