The Coat:
The Model 1879 Officers Full Dress frock coat came in three different variations. The Model 1879 Company Grade Officers Frock coat was made of dark blue wool with 14 buttons sewn in two columns of seven, evenly spaced from neck to waist. Each button has the arms of the United States on its face with a letter for the corps of service in the middle of the shield on the eagle's chest (for example, an "I" for the Infantry, an "A" for artillery and a "C' for cavalry). If an officer was not assigned to the infantry, the cavalry or artillery branches, the button design could be just the plain Arms of the United States, to represent general services, or it may be very specialized, such as the design used for the Corps of Engineers. The tail flaps of the frock coat had pockets within each flap, with a button at the top and bottom of each flap.
The second variant, that for field grade officers, was identical to that used by the lower ranks, but had 18 buttons sewn in two columns of nine.
The third variant, that for general officers, was also basically identical, except the collar and cuffs were of dark blue velvet and the buttons were of the general service variety. The buttons were set in one of the following patterns indicating the wearer's rank:
General - Two columns of twelve buttons, set in groups of four.
Lieutenant General - Two columns of ten buttons, set in groups of three-four-three.
Major General - Two columns of nine buttons, set in groups of three.
Brigadier General - Two columns of eight buttons, set in pairs of two.
To indicate an officer's rank, shoulder knots were worn. The knots would have a velvet background in one of only four colors: white for Infantry, red for Artillery, yellow for Cavalry and black for all other officers. A gilt cord wrapped around the pad's outer edge three times and forms a double "figure eight" on the narrow end around the attachment post, which had the same design as the frock coat's buttons. The regiment number (such as a "1" for the 1st U.S. Infantry Regiment) would be embroidered in the pad's center. The rank insignia was embroidered on both sides of the regiment number. All second lieutenants had only the regiment number in the pad's center, while a colonel had only a silver eagle on the pad without a regiment number.
For a general officer, epaulets were worn. Epaulets are very ornately embroidered insignia worn on the shoulders, made of gold bullion thread with bullion fringe. Rank was indicated as follows on the epaulets:
General - Two five-point stars on either side of the Arms of the United States
Lieutenant General - Three five-point stars
Major General - Two five-point stars
Brigadier General - One five-point star