He was successively private soldier and accountant for his company, quarter-master, 2nd Lieutenant of the line, Captain of the line, and finally Adjutant General of the 2nd Louisiana Brigade, A. N. Va., under Lee and Jackson, with rank of Major. On May 4, 1864, Adjutant General Handerson was taken prisoner, and from May 17th until August 20th he was imprisoned at Fort Delaware in the Delaware river. He was then confined in a stockade enclosure on the beach between Forts Wagner and Gregg on Morris Island, until about the end of October, when he was transferred to Fort Pulaski at the mouth of the Savannah river, and in March, 1865, back to Fort Delaware. In April, after Lee's surrender, many of the prisoners were liberated on taking the oath of allegiance to the Federal Government. But Handerson did not consider his allegiance to the Southern Confederacy ended until after the capture of President Davis, and it was not until June 17, 1865, that he signed the oath of allegiance and was liberated in Philadelphia. Since that time, with that spirit of tolerance and openness to truth which characterized the man, he has said, "in the triumph of the Union, the war ended as it should have ended." Mr. Handerson then resumed his medical studies, this time in the College of Physicians and Surgeons of New York, Medical Department of Columbia University, taking the degree of M.D. in 1867. Hobart College conferred the A.M. in 1868. On October 16, 1872, he married Juliet Alice Root, who died leaving him a daughter. February 25, 1878, Dr. Handerson read before the Medical Society of the County of New York an article entitled, "The School of Salernum, an Historical Sketch of Mediaeval Medicine." This essay attracted wide attention to his scholarly attainments and love of laborious research. For example, Professor Edward Schaer of the chair of Pharmacology and Pharmaceutical Chemistry, of Neumuenster-Zuerich, pronounces this pamphlet "a valuable gift ... a remarkable addition to other historical materials ... in connection with the history of pharmacy and of pharmaceutical drugs"; that he found in it "a great deal of information which will be sought for in vain in many even renowned literary works." Dr. Handerson practiced medicine in New York City, from 1867 to 1885, removing to Cleveland in 1885. On June 12, 1888, he married Clara Corlett of Cleveland. Then in 1889 appeared the American edition of the "History of Medicine and the Medical Profession, by Joh. Hermann Baas, M.D.," which was translated, revised and enlarged by Dr. Handerson, to whom, in the words of Dr. Baas, "we are indebted for considerable amplification, particularly in the section on English and American medicine, with which he was, of course, better acquainted than the author, and for numerous corrections." ... As a matter of fact, the learning and judgment, and the conscientious industry of the translator and American editor of this work are evident throughout the book.