The first Steam Sapper was ordered from Aveling & Porter in 1868. Steam sapper number 1 was required to operate a circular saw, grindstone, lathe and joiner as well as drawing 5 tons up a 1 in 12 slope. It performed this, but was more than a quarter of a ton over the specified maximum weight of five tons. The heaviest field gun in use at that time was the 64 pdr Armstrong breech loading siege gun weighing . Since pontoon bridges would be constructed to support this gun, steam sappers were required to weigh less than the gun so that they would not overload the bridges. Steam sapper number one had a loading on the rear wheels less than this, and so was accepted.