Inspired by the meetings her mother used to hold for local mothers at their home in Herefordshire, and her struggles after the birth of her own daughter, Mary Sumner founded the Mothers' Union in 1876. Intended as a Christian group to support mothers and to nurture the family, the Union rapidly spread across the United Kingdom and in 1897, Queen Victoria became a patron. The association then opened branches throughout the British Empire, including in New Zealand, Canada and India. Sumner led the Mothers' Union until her death in 1921 at the age of 92.

Throughout the twenieth century the Mothers' Union continued to expand across the world, and now has four million members in 84 countries. The group's mission include supporting disadvantaged families, promoting Christian values, and campaigning on an international level.

During the first half of the twentieth century, membership of the Mothers' Union soard from 169,000 in 1900 to half a million in 1950. Shortly after hitting the 600,000 members mark, the association produced a commemorative map showing their global presence. Made by map publisher Francis Chichester, the map highlights the expansion of the Mothers' Union across six continents, with red lines delineating areas where its branches were located. There appear to have been no members in the United States, Scandinavia and the U.S.S.R. 11 illustrations across the map depict native mothers, including an American Indian in southern Canada and an Aboriginal family in Australia.

The border displays 22 crests depicting the different countries or regions in which there were members of the Union, illustrated with the land's coat of arms, its flag or a representative vignette. In the lower centre is a portrait of Mary Sumner flanked by images of Mary Sumner House, in London, which continues to serve as the group's headquarters, and the chapel within.