"Mantle" can also refer to the extant city of Mantle, the former capital of the Kingdom.
Originally founded by settlers who travelled north, Mantle was well-protected from the Grimm due to the harsh, cold conditions. The climate's hostility also forced the people of Mantle to adapt quickly in order to survive and led to the development of new Dust technologies.
Around eighty years before the beginning of the series, a massive ten-year conflict known as the Great War came to an end. In this war, Mantle and Mistral fought Vale and Vacuo. Prior to the war, Mantle formed an alliance with Mistral. The two traded frequently, and Mantle taught Mistral how to form settlements in the snowy northern region of Anima.
After an incident with the Grimm, Mantle came to the conclusion that, if it controlled its citizens' emotions through the abolishment of the arts and self-expression, it would become safer from Grimm. Rather than lose the alliance, Mistral did the same to an extent. This added to the list of things Vale disliked about Mantle and Mistral, among which was the treatment of their own citizens, their use of slavery and their insistence that their way of life was what was best for everyone.
Eventually, Mistral got into a conflict with Vale after a riot between settlers from the two evolved into the first battle of the Great War. Mantle rushed to their ally's aid, and together, they fought Vale on both Sanus and Anima soil. Having established a presence in Vacuo, the two allied kingdoms were able to keep Vacuo out of the conflict, and some time into the war, they began pressuring the desert kingdom to join the war on their side. Fearing the two kingdoms would conquer Vacuo if Vale fell, the citizens of Vacuo pushed Mantle and Mistral out of their territory and allied themselves with Vale.
Grimm attacks increased worldwide, and as a result, Mantle lost many of its settlements to the creatures, some of which were never reclaimed.
During the war, Mantle accelerated the pace of its technological innovation, developing new weapons and applications of Dust, giving them an edge during the conflict. Large tracts of land were set aside for Dust mining and research. The Kingdom was also home to at least one combat school, Alsius, located to the northeast of the main settlement. The territory surrounding Alsius was used as a research and development facility during the war.
The Great War finally came to an end with the deadliest battle in the war's history. Mantle and Mistral attempted to take Vacuo's Dust mines to cut off their enemy's supply. There, they were met with the king of Vale personally leading his army alongside Vacuo. It is said he laid waste to countless men, but historians claim unusually violent weather and Mantle's inexperience in desert combat aided this feat.
With the war over, the leaders of the four kingdoms gathered on neutral ground on Vytal to form a treaty and plan the future of Remnant. There, they restructured the four kingdoms' governments, they redistributed territories, abolished slavery and began the tradition of the Vytal Festival and the king of Vale founded the four Huntsman Academies.
Alsius was reopened under the name Atlas Academy and was secretly given a Relic to safeguard. In an attempt to give back to its citizens, Mantle applied many of the techniques and technologies used in the war to enhance the Huntsman Academy's campus, expanding the school grounds and even securing the surrounding areas. Along with the eventual establishment and merging of the military and research facilities with the government and schools, the original capital of Mantle was overshadowed. The decision was made to move the capital to Atlas, and the Kingdom as a whole was also accordingly renamed to Atlas.
Mantle, as former capital, appears to have subsequently fallen on hard times as alluded in Word of Remnant: Atlas. During the charity concert in "Tipping Point", guests converse with Jacques Schnee about the economic disparity between the cities of Atlas and Mantle. At the same time, they discuss Faunus-Human relations; it is implied that a significant portion of Faunus live in the poorer city of Mantle and are economically disadvantaged themselves. The Schnee Dust Company, among others, promised those who moved to the city of Atlas jobs, though it is implied that this is not working out as well as the immigrants would have hoped.
- While the main four Kingdoms are represented by a distinct color, Mantle appears to have more than one color associated with it. In the RWBY: World of Remnant episodes "Atlas" and "Vacuo", representatives of Mantle are generally color-coded as dark gray-blue (distinct from the more saturated blue of Mistral) but the first settlers of the land are also shown as both white and blue-green. In earlier World of Remnant episodes, they were color-coded white, the same color that represents the successor state of Atlas.
- In Remnant: The Game, units from Mantle have a repair time of only one turn under certain conditions.