Today marks the 100-year anniversary of the first use of the tank in warfare.
Rushed into action during the Battle of the Somme, the Mark I tank was developed in response to the appalling conditions on the front. It was designed to cross trenches and resist small arms fire and it was hoped it would help allied forces break the bloody stalemate that had developed.
David Willey, from Dorset Tank Museum, said:"The British Army sent its new 'secret weapon' into action - and it did so in order to prevent the sort of casualties experienced on that first day of the battle."
Commemorating the anniversary today, a replica Mark IV tank supplied by Dorset Tank Museum, was placed in Trafalgar Square.