Henry Lewis Rottger and John Mueller, great-grandfather and grandfather of John Hyatt, both served in the Union Army during the Civil War. Henry Lewis Rottger, born in 1818 in Hanover, Germany, was a boot maker. He became a citizen of the United States on April 19, 1837, and enrolled in the army in April of 1861. He served two years, but was later discharged by the Surgeons Certificate of Disability in April of 1862. Henry Lewis Rottger re-enlisted on September 18, 1862 to serve for three more years in the Commanding 5th Regiment N.Y.S.V. John Mueller was born in 1842 in Nassau, Germany. He enrolled in the army on July 24, 1861 and served three years as a Private. After serving the maximum three years as a volunteer, he was discharged from the army in Maryland on July 25, 1864. He re-enlisted and was paid for his duties beginning in August 1864 and continuing through October 1867. John Mueller became a citizen of the United States on September 21, 1885 at the age of 43. At the time of his death, he was a colonel in the New Jersey National Guard and a member of the staff of New Jersey governor, Robert S. Green.
From the description of John Hyatt Collection, 1837-1887. (New Jersey Historical Society Library). WorldCat record id: 60386894
