Hermann Bannse came west on the Oregon Trail at age 17 with "Dr. Keil's Colony" in 1855. His future wife Margaret Bergman was also in the wagon train.
Sophia Bannse Hagar (Dr. Keil's sister) had one child from her first marriage in Germany, with her first husband, Conrad Bannse -- Herman Bannse. She remarried in Germany to William Hagar and emigrated to the United States.
William and Sophia Hagar are shown living at Aurora, Oregon, in the June 14, 1860 census with their son Herman, just about two months before he married Margaret.
Herman Bannse married Margaret Bergman at Aurora on August 8, 1860. The Justice of the Peace was James Barlow. Herman returned to Aurora for two weeks in February and March of 1861. Perhaps his wife was with him as both of their mothers were living there.
Sometime prior to the 1870 Census Herman and Magaret moved to Bucoda, WA, which became their permanent home.