In accordance with the appointment of the Aizu domain Lord Katamori MATSUDAIRA as Kyotoshugoshoku (Military governor of Kyoto, to counteract the growing Sonno Joi (the 19th century slogan advocating reverence for the Emperor and the expulsion of foreigners, which was centered in Kyoto) in 1862, HIROSAWA moved to Kyoto in advance to the arrival of the lord Katamori in order to investigate the situation of Kyoto.
文久2年（1862年）、会津藩主松平容保は京都守護職に任ぜられ、広沢は先んじて上京し京都の情勢を探った。