During World War 2 John Deere built two prototype military tractors for the United States Army. These were modified 1940 Model A Row Crop tractors. They were built at Waterloo and were designated Army A1 and Army A2. They were sent to the military proving grounds where they were tested for several weeks to see if they would be a variable product for the military. No one knows what happened to the original prototypes, but several passionate John Deere collectors built two replicas of the historic tractors.