While other participants in the fighting invented various towers to raise a man above with binoculars - the Germans strained their heads and logically assumed that the periscope from the submarine was in general no worse - and it was not afraid of bullets.
the 25 meter tall sliding mast for the eight-knee lens was made, but thin - and an open optical channel was used to transmit the image.
The mast periscope was designed for observing over obstacles of between 30 and 85 feet in height, and could be rapidly erected or taken down and transported on its carriage. It essentially consists of three parts, namely a steel telescopic mast, and upper and lower optical systems that are attached to it.
The telescopic mast is carried on trunnions on the carriage and travels in a horizontal position. The mast contains seven tubes which can be raised or lowered within each other by means of a cable attached to a winch, and when erect, the mast was steadied by three guy ropes.
they even used them in trench warfare