Samuel Forster Tappan was born in Manchester-by-the-Sea, Massachusetts on June 29, 1831. From a family of merchants, philanthropists, and abolitionish, Tappan arrived at and established Lawrence, Kansas in August 1854 with other members of the New England Emigrant Aid Company.

Tappan remained in the Kansas Territory during the border wars, supporting the free state movement and discovering the altered election returns in 1858 at Lecompton. He also served as secretary at both the Leavenworth and Wyandotte constitutional conventions and participated in rescuing Free-Stater Jacob Branson during the 1855 Wakarusa War.

In 1860 Tappan moved to the Colorado Territory, settling in an area that would become Denver. He worked as a journalist and then store owner and, after the outbreak of civil war in 1861, petitioned to raise a regiment of volunteer Union troops. Tappan was promoted to lieutenat colonel and placed in charge of Fort Wise. He was later demoted and placed in command of Fort Garland.

In 1864 Tappan was appointed the head of a military commission investigating Colonel John Chivington's involvement in the Sand Creek Massacre, in which Chivington led an attack against a Cheyenne and Arapaho camp and killing approximately a third of the men, women, and children in the camp. Tappan remained involved in promoting legislation considered favorable to Native Americans into the 1870s. He was involved in the Indian Peace Commission of the 1860s, in which he attempted to help negotiate several treaties with Navajo, Lakota, Cheyenne, and other tribes, treaties with a focus on "civilizing" and assimilating these indigenous peoples.

In 1868 Tappan married the spiritualist Cora Lorencia Veronica (Scott) Hatch Daniels, who had been born in 1840 in New York. He was her third husband, and they later divorced. He also adopted a Cheyenne girl after the Washita River Massacre led by General George Custer and named her Minnie Tappan. She died while studying at Howard University.

Tappan spent time in Pennslyvania and Washington, D.C. and encouraged emigration to Oregon. He died January 6, 1913 in D.C. and was buried in Arlington National Cemetery.

[Information retrieved from findagrave.com and finding aid for the Samuel Forster Tappan collection, MSS.617, History Colorado, Denver, Colorado.]