When fighting began to get bogged down in the trenches, the Great War saw the re-emergence of old forms of combat inherited from the tradition of siege warfare as practiced in Vauban’s day (17th-18th centuries). But this new state of affairs also proved to be a tremendous catalyst to innovation, with examples including the evolution of civil and military aviation, submarines doing battle at sea and the exponential development of heavy artillery. Some of the more fanciful and unworkable innovations, such as the Dragon of the Somme, would not get beyond the experimental stage. Others, particularly those innovations which held the promise of breaking the stalemate of trench warfare and getting back to open warfare – tanks being the prominent example – would develop at an extraordinary pace.