Gustav Adolf Bergenroth (26 February 1813, Oletzko, East Prussia – 13 February 1869, Madrid) was a German historian.
He was born at Oletzko, in East Prussia, on 26 February 1813. From his father, the magistrate of the town, a stubborn and incorruptible patriot, he received an education well calculated to develop the independence of mind and strength of body for which he was remarkable all his life. After a somewhat stormy career at the university of Königsberg, he successively obtained several minor situations in the magistracy, and devoted himself to the study of statistics and political economy. His inquiries, combined with the restless temper which always made official life distasteful to him, led him to adopt advanced democratic opinions, which, freely manifested during the Revolutions of 1848, cost him his post in the civil service upon the triumph of the reaction.
After assisting in Gottfried Kinkel's remarkable escape from Spandau Prison, be determined to emigrate to California, whither he proceeded in 1850. The incidents of his voyage and residence were most adventurous. He caught yellow fever on the passage out, was robbed, while unconscious, of all his property, arrived at San Francisco half dead, and owed his life to the charity of a woman. Having also recovered from an attack of cholera, he betook himself to the wilderness, and lived for some time the life of a hunter. He saw much of the operations of the vigilance committee, which he subsequently vividly described in Household Words.
In 1851, he returned to Europe, and led for several years a roaming life, seeking employment alternately as a tutor and as a man of letters. In 1857, he formed the resolution of devoting himself to English history, and settled in London with the view of studying the period of the Tudors. Finding the materials in the English Record Office insufficient, he conceived the bold plan of establishing himself at Simancas, and making a thorough examination of the Archivo General de Simancas, at that time exceedingly difficult of access. Before Bergenroth not more than six students, Spanish and foreign, had made any important research in the archives, and it was generally believed that great havoc had been committed among them by the French soldiers, which Bergenroth found reason to doubt. The history of his investigations is most graphically narrated by himself in letters to the Athenæum, and in private communications to Sir John Romilly, master of the rolls, who was induced by the Athenæum letters to procure Bergenroth a commission with a stipend from the English government.