There have been so many amazing discoveries and inventions in the history of mankind that one would be hard put to place them in order of importance. Many have revolutionized the way society works, such as the microchip, but a modest case could also be made for the humble farm tractor. Without it, it would be impossible to produce the vast quantities of food consumed by an overwhelmingly urban population that, with little thought as to its origins, takes it for granted that food will magically appear. For this reason alone, the tractor must qualify as a small but essential cog in the vast machine that is the modern world. The first powered farm implements in the early 1800s were portable engines, steam engines on wheels that could be used to drive mechanical farm machinery by way of flexible belts. Around 1850, the first traction engines were developed from these, and were widely adopted for agricultural use. Where soil condition permitted, as in the USA, steam tractors were used to direct haul plows, but plowing engines were used for cable hauled plowing in the UK and elsewhere. Steam powered agricultural engines remained in use well into the 20th century until reliable internal combustion engines were developed.