Following the collapse of the Confederacy and the surrender of the remaining Texas forces, Robertson returned to his home in Independence and resumed his medical practice, a period marked by mourning when his wife died in 1868. He re-entered politics in 1874, being named as superintendent of the Texas Bureau of Immigration for two years. Two years later, he served as passenger and emigration agent for the Houston and Texas Central Railroad. Robertson married a widow, Mrs. Hattie Hendley Hook, in 1878 and relocated to Waco a year later. There, he continued to promote railroad construction in west Texas.