That question has THREE possible answers! In 1912, Deere & Co. began to develop prototypes for their own tractor. The only one that ever went into production (in 1918) is now known as the "Dain" tractor. It is named after Joseph Dain, the engineer who designed it. Only 50 to 100 or so "Dain" tractors were built and sold, BECAUSE.... That same year the Deere Company bought the Waterloo Engine Company, in order to obtain a factory in which to build tractors.
The Waterloo Engine Company was already manufacturing the Waterloo Boy tractor that it had introduced in 1913. The "Dain" project was halted for two reasons: Joseph Dain had died, and the Waterloo Boy tractor was less expensive to build than the "Dain". Deere & Co. elected to continue manufacturing the Waterloo Boy tractors until 1924. This gave them plenty of time to develop a completely NEW tractor of their own. It was called the Model D. and it was introduced in late 1923 as a 1924 Model.

So.... take your choice:

The "Dain" was the first tractor with the John Deere name on it, but very few were produced. It was not a commercial success.

The Waterloo Boy tractors were produced by the THOUSANDS by Deere & Co. between 1918 and 1924.