People have been aware of and worked iron for approximately 4,000 years. However, its usage only became recognized around 1200 BC. This is because it was extremely difficult to smelt, melt, cast or forge because of temperature required.
The ancient Chinese found that the use of a dual air-blower box elevated the temperature of the iron. The source of the thermal energy was a fire made of wood and charcoal. They did not realize the fact that while the iron was being heated in the fire, it was also absorbing carbon from the wood and charcoal fire. With this treatment, it was transforming from iron into what we know today as steel - an alloy of iron plus carbon.
In the country of India, the Indian blacksmiths (3,500 years ago) developed a material they called "Woodtz" iron. This was simply iron plus carbon (steel). This steel was used to make agricultural implements and weapons. Steel soon edged out bronze because it could be made harder and stronger. Excavated evidence of implements from the ancients has been microscopically examined, and it has been seen that martensite was present, especially in the near-surface areas of the artifact.
Martensite was so named after Adolph Martens, who was a German engineer that made some interesting observations with a microscope at 400X magnification. There were many other metallurgical engineers who made significant contributions to the observation of martensite and how it is formed, but Martens got the naming rights.