Shirt - Research.

The shirt has been an essential undergarment for men throughout history and has slowly developed over time whilst maintaining a couple of main aspects. The sleeves have always remained long and the shirt length no longer than hip length. Around the 18th Century gussetts were added to the shirt sleeves to allow extra movement, and the collar was shortened to touch the jaw line rather than the cheeks to allow a more free movement for the head. A high standing collar (much like my design) would usually have a cravat tied beneath it.

From The History Of Underclothes by C. Willett Cunnington, 1981.