aachen adolf hitler air superiority allied advance from paris to the rhine alloy archaeology battle of france battle of the bulge billy joel biotope bomb bunker camouflage carbine casemate concrete echternach eifel embrasure environmentalism france fritz todt geilenkirchen german empire germany gun turret hans von luck hindenburg line kleve land mine libya limes limes germanicus locarno treaties luxembourg maginot line molybdenum monschau monument nazism netherlands nickel normandy organisation todt poland propaganda reichsarbeitsdienst rhineland right-wing politics ruins saarland shrapnel steel switzerland tobruk treaty of versailles viersen weil am rhein wikimedia commons world war i world war ii