Built by German steelmakers Krupp, K5 railway guns were positioned in Northern France from 1940 onwards originally to provide fire support for Operation Sealion (the German invasion of Britain) and later to fire 28cm shells across the English Channel to Dover.
Only 25 of these guns were built and several were positioned around northern France, travelling along lines from Calais to Boulogne-sur-Mer.
The gun barrel itself is over 25 metres long with each shell weighing over 240kg (530lb). They could be fired over 60km (nearly 40 miles!).
The shells themselves were so heavy that a crane was incorporated into the railway gun’s structure and this was positioned on top of a generator unit to the rear of the barrel. This power plant would provide the means to raise the barrel too.

This K5 - located at the superb Batterie Todt Museum near Audinghen - is an mixture of two guns found in southern France in the 1970's and transported to the museum. It is one of just two remaining in the world today, the second one is on display at Fort Lee, Virginia, USA.