The term redskin is slang for Native Americans, used since the colonization of North America by Europeans. It is often considered to be offensive.
The National Vietnam Veterans Readjustment Study, conducted by the US government, found that people of color or minorities had a much harder time adjusting to life after the Vietnam War due to abuse in Vietnam. Many Native Americans were looked down on and nicknamed "Chief". They were often stationed in the most hostile areas, with dangerous duties such as walking point or being "tunnel rats."