E. Remington & Sons, a company that was then primarily known for manufacturing firearms, purchased Sholes's patent in 1873. After making a few additional mechanical improvements, like adding a Shift key to allow typists to switch between capital and lowercase letters, Remington began mass-producing typewriters that featured the QWERTY layout, with the intent of selling them to the business market, in 1874. -- Josh Kaufman: The First 20 Hours, Portfolio / Penguin (2013).
Wrong. E. Remington & Sons manufactured the first commercial typewriter in September, 1873, but they did not purchase Sholes's patents (cf. John A. Zellers: The Typewriter - A Short History on Its 75th Anniversary 1873-1948, Newcomen Society of England American Branch, New York (1948)). The first typewriter with upper and lower case letters was Remington No.2 that was introduced in January, 1878, as I mentioned before.