WWI: German Imperial Navy Admiralstab Map Calais 425 (Huge Vintage Glass Plate Negative 18x13CM 1910s)

spectacular and very large original historical military glass plate negative measuring approximately 18 x 13 cm. this rare half plate master record is an official secret military target map documenting the french port city of calais.
the map plotted at a scale of 1:20000 was engraved and printed by the imperial german navy admiralstab der marine gedruckt im admiralstab der marine based on cartography by wagner and debes, leipzig. it includes a highly interesting tactical bombing and artillery key at the bottom stating blau zu schonen, rot zu zerstoeren blue to be spared, red to be destroyed for strategic operations. the map showcases detailed layouts of the calais harbour, docks, fortifications, fort risban, the citadel, railway lines, and main city streets.
the upper right corner of the plate features the contemporary hand-scratched military archive registration code 425.
the glass plate is in very good vintage condition with outstanding line definition, crisp text contrast, and a fully intact emulsion. a supreme museum-grade artifact for advanced collectors of WWI naval intelligence, military cartography, zeppelin bombardment targets, and the history of the western front. 

size: ~ 18 x 13 cm (1 cm ~ 0.39 inch)

condition: very good...please also refer to scans which show complete glass plate

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