for the design and construction of the wall's major gun emplacements and fortifications.

The OT supplied supervisors and labour as well as organising supplies, machinery and transport to supplement the staff and equipment of construction companies. Many of them were German, however construction companies in occupied countries bid for contracts. Companies could apply for OT work or could be conscripted. Companies failing to complete their work on time, which was always possible as the OT controlled the material and manpower of each firm,