Short answers, pulled from the story.
Brown can be produced by mixing red and yellow with blue. In the RGB color model used for screens, brown is made by combining red light at low intensity with green light at an even lower intensity, with blue light also present. In the CMYK model used in printing, brown is typically produced by combining yellow ink with smaller amounts of magenta and black inks.
The first recorded use of brown as a color name in English was in the year 1000. The term derives from Old English brún, which originally meant any dusky or dark shade. The current, more specific meaning developed in Middle English from the fourteenth century.
The Nazi Party chose brown largely for convenience. Large quantities of war-surplus brown uniforms from Germany's former colonial forces in Africa were cheaply available in the 1920s. The color also suited the working-class and military image the party wished to convey.
Umber is among the oldest pigments known. It is a brown clay composed of iron oxide and between five and twenty percent manganese oxide. Paintings made with umber have been dated to 40,000 BC.
Brown is the least popular color in public opinion surveys conducted in Europe and the United States. Only one percent of respondents named it their favorite color, while twenty percent called it their least favorite.
Khaki is a yellowish shade of tan, its name drawn from the Urdu word for dust-colored, which in turn came from an earlier Persian word for soil. Indian soldiers of the Corps of Guides in British India began wearing it in 1846. The British Army adopted it for the Abyssinian Campaign in 1867-1868, and the United States Army adopted it during the Spanish-American War in 1896.