Tanks in World War I
The continued need for four men to drive the tank was solved with the Mark V which used Wilson's epicyclic gearing in 1918. Also in 1918 the French produced the Renault FT, the result of a co-operation between Estienne and Louis Renault. As mentioned before, it had the innovative turret position, and was operated by two men. At just 8 tons it was half the weight of the Medium A "Whippet" but the version with the cannon had more firepower. It was conceived for mass production, and the FT became the most produced tank of World War I by a wide margin, with over 3,000 delivered to the French Army. Large numbers were used by the Americans and several were also lent to the British.
Mine flail
However, tanks have the disadvantage of having the driver at the front, close to the flail and any explosions, and they can not go slow enough for effective mine clearance. Also, the weight of tanks makes them difficult to transport (by contrast, the 18-ton Hydrema 910 is light enough to be moved by air in a C-130 Hercules.) The tanks used have generally been obsolete models that have been highly modified - some work under remote control, others have had the driver's station moved to the rear. In modern times, there has been little military interest in an updated equivalent of the Sherman Crab or Matilda Scorpion - a substantially unmodified tank still capable of combat. In battle, the modern preference is to detonate mines with explosive devices (mine-clearing line charges), such as the Antipersonnel Obstacle Breaching System or the Giant Viper. During the Gulf War, the U.S. 2nd Marine Division made an attempt to breach an Iraqi mine field with a mine flail mounted on an armored bulldozer. But the flail was destroyed and the bulldozer crippled by an Iraqi anti-tank mine.