Hermann Altgelt was born on July 17, 1832, at Düsseldorf on the Rhine, the son of a privy counselor of that city. Upon completing military service, he immigrated at age twenty to New Orleans and worked briefly for the cotton firm of John Vles. In 1854 he led a surveying party into the Hill Country of Texas and laid out the town of Comfort on property owned by Vles. Soon, German freethinkers from New Braunfels began to settle in the area and to develop the communal life that they wanted. The Comfort area, in spite of floods and drought, offered lands for both farming and ranching, as well as an abundance of timber and water. Altgelt began lumber and grist mills, but neither was successful. He married another immigrant from the Rhineland, Emma Murck (see ALTGELT, EMMA MURCK), in July 1855 and thereafter took up the practice of law. Though he was never a fire-eating supporter of secession, during the Civil War Altgelt aligned himself with the Southern cause. He traveled to Germany, allegedly as a result of strained relations with his fellow countrymen. After this trip he joined the Confederate Army in time to participate in the battle of Palmito Ranch after Lee's surrender.
He moved to San Antonio in 1866, continued his practice of law, and increased his real estate investments. According to some sources, he built the first house on King William Street (see KING WILLIAM DISTRICT, SAN ANTONIO) in 1867 and was thus accorded the privilege of naming the street, allegedly after Wilhelm I of Prussia. His neighborhood rapidly attracted successful families of German and other nationalities. Altgelt built a more elaborate second home in 1877–78 at 226 King William Street. He died on March 28, 1878, at the family ranch, Wassenberg, twenty-five miles from San Antonio. Altgelt had nine children, seven of whom grew to maturity.