First, let me mention that details on the history of crop modification can be found in the Explore section of GMO Answers. And, as described in the History of Crop Modification reel, plants have been genetically modified through conventional breeding for centuries.
The first use of biotechnology involving transformation and recombinant DNA technology, or what is commonly referred to as GM, at Monsanto was research work with E. coli for producing proteins in the laboratory in the 1970s. This use of genetic modification for generating proteins is best known for medical uses, such as insulin for diabetics and growth hormone for growth insufficiency. In addition, other organisms, such as microbes, have been modified for common fermentation uses, such as cheese and beer production. Monsanto does not commercialize any products related to these uses of biotechnology.
The first modification of plants through the use of genetic engineering at Monsanto was petunias in the 1980s. These were not marketed but were used for research purposes, due to the fact that they could be transformed and the genetics were relatively well known. The first major GM plant products commercialized in 1996 were Roundup Ready soybeans and Bollgard cotton. Roundup Ready soybeans were developed to provide growers with a tool to more effectively control weeds, while Bollgard cotton was developed to protect plants from bollworm and certain other insect pests.