Ralph Sandiford Man, cofounder of Mansfield, was born in Charleston, South Carolina, on November 21, 1825, the son of John and Catherine (Norton) Man. He left Charleston in 1847 and arrived in Harrison County, Texas, three years later. In 1854 he moved to Fort Worth. With his partners Julian Feild and David Mauck, he constructed a water-powered mill close to the confluence of the Clear Fork and the West Fork of the Trinity River. When the water source failed, Man moved to the Walnut Creek settlement in southeastern Tarrant County. In 1859, with help from local settlers and brickmaker S. W. A. Hook, he and Feild began construction of another mill, which was completed in 1860. This gristmill, still operative after the turn of the century, was powered first by horses, then water, then steam. Through government contracts it supplied a vast area from Fort Sill to the Rio Grande and from Fort Belknap to the Sabine. It was required by the Confederate government in 1861 to supply flour to the Confederate Army. The mill attracted settlers to the area, which as early as 1860 had become known as Mansfeild. Soon Man and Feild opened a local mercantile store. The town was incorporated as Mansfield in 1890.
Man returned to Harrison County in 1863 to marry Julia Alice Boisseau, the sister of Feild's wife, Henrietta. They had two children. Julia died in 1868, shortly after their home at Walnut Creek was built. In 1870 Man purchased the 368-acre farm upon which his home was built. He subsequently married Sarah Jane Stephens, and they had four children. His second wife died in 1880. Man was a member of the Walnut Creek Congregation of the Cumberland Presbyterian Church, which formally became the Mansfield Congregation in 1869. He served as session clerk of this church from 1872 to 1881. In 1874 he donated 2.75 acres to the Cumberland Presbyterian Church to be used as a cemetery. Man was a Democrat and a member of the Mansfield Masonic Lodge. He remained active in the mill until the mid-1890s and lived in Mansfield until his death from cancer in 1906.