The Bielefeld Viaduct

The defences

The viaduct was protected by an air observation post on the highest point in the area. To conceal the bridge against attack, a 'Nebel-Kompanie' with smoke generators was stationed two miles north east of the viaduct in a field near the River Aa.

A 20mm flak gun battery manned by 24 teenage boys was set up on the slope above the viaduct and a Vierling cannon was on the viaduct itself. 

The feared Vierling 20mm gun

The young crews for these weapons were billeted in nearby huts.