Henry Reed Rathbone was born on July 1, 1837, in Albany, New York, to Jared L. Rathbone, a successful merchant and mayor of Albany, and Pauline Rathbone (née Penney). After his father's death in 1845, his mother remarried U.S. Senator Ira Harris in 1848. This union made Clara Harris, Ira's daughter from his previous marriage, Henry's stepsister. Henry and Clara developed a close relationship and eventually became engaged. During the American Civil War, Henry joined the Union Army in 1861, achieving the rank of major. He participated in significant battles, including Antietam and Fredericksburg. ​

On April 14, 1865, Henry and his fiancée, Clara Harris, accompanied President Abraham Lincoln and First Lady Mary Todd Lincoln to Ford's Theatre. During the performance, John Wilkes Booth entered the presidential box and fatally shot President Lincoln. Henry attempted to apprehend Booth but was severely wounded when Booth stabbed him with a dagger. This traumatic event profoundly affected Henry's mental health. ​

Henry and Clara married on July 11, 1867, and had three children: Henry Riggs Rathbone, Gerald Lawrence Rathbone, and Clara Pauline Rathbone. Despite resigning from the Army in 1870 and settling in Washington, D.C., Henry's mental health deteriorated over the years. He exhibited erratic behavior, including jealousy and paranoia, believing that Clara intended to divorce him and take their children. In 1882, President Chester A. Arthur appointed Henry as the U.S. Consul to Hanover, Germany. The family relocated there, but Henry's condition worsened. ​

On December 23, 1883, in a delusional state, Henry attacked Clara, fatally shooting her in the head. He then attempted to harm their children but was thwarted by a servant. Afterward, Henry attempted suicide by stabbing himself multiple times but survived. He was charged with murder but was declared insane by doctors and committed to an asylum for the criminally insane in Hildesheim, Germany, where he remained until his death on August 14, 1911.