Late in WW1 the US determined that there was a problem with current tanks. The British designed rhomboid tanks were good at crossing the enemy trenches but were so heavy that most got stuck or broke down in no-mans-land. The French FT17 light tank usually made it across no-mans-land but couldn't always cross the enemy trenches. The US looked for a tank that could do both. Pioneer Tractor Company tried to solve the problem by hollowing out the rhomboid. The tank used standard iron pipe and plumbing connectors as a frame with an armored engine/fighting compartment suspended in the frame. Pioneer completed a prototype in October 1918 and submitted it for testing. It was fast by WW1 standards and crossed the trenches well. However, its limited ability to carry armament doomed the project. The single prototype is preserved at Ft. Lee.