The regimental history of the 7th Vermont Vols., written by William C. Holbrook, contains some pages remembering John Q. Dickinson. The description of Dickinson's time in Florida is not attributed to any witness or first person source and, consequently, is more significant for the impressions it conveys, rather than any factual information contained. First the excerpt with my comments following:
FROM: A NARRATIVE OF THE SERVICES OF THE OFFICERS AND ENLISTED MEN OF THE 7TH REGIMENT OF VERMONT VOLUNTEERS (VETERANS) FROM 1862 TO 1866
by William C. Holbrook (New York, 1882)
 CAPT. JOHN Q. DICKINSON
On September 13th,  Lieut. John Q. Dickinson, who for some time had acted as regimental Quartermaster, was commissioned as such. He discharged the duties of that office, which were by no means light, very acceptably to the regiment and with much fidelity and ability. He was subsequently made Captain of Company F, and was honorably discharged for disability October 10th, 1865. Upon leaving the service, like many other of the Union soldiers, he elected to cast his lot with the people of the South. For a time he was engaged in the lumber business in Florida in partnership with Col. D.. B. Peck. But after a little they relinquished that business and Col. Peck returned to the North. Capt. Dickinson, however, remained in Florida, and entered somewhat into politics, and finally secured a public office at Mariana, I believe. He was an educated gentleman, and a facile and pleasing writer. In disposition he was as agreeable as he was amiable, and was the last against whom it would be expected that any one would harbor harsh or hostile feelings. Nevertheless, it seems that his superior attainments did occasion much hatred and jealousy on the part of the Floridians of the neighborhood, who wanted no "Yankees" to administer their affairs, or to hold office in their State. A trifling newspaper article, or something of the kind, was seized upon as a pretext to inform Mr. Dickinson that his presence was not wanted at Mariana, and accordingly a notice, emanating from that most fiendish and hellish of all organizations, the Ku Klux Klan, was served upon him in due form, whereby he was warned to depart under the penalty of death. To this threat he paid no attention.
TRAGIC DEATH OF CAPT. DICKINSON.
His friends, however, were so apprehensive of the great danger he incurred, that they entreated him not to let it pass unheeded, and urged him to return home. But he was not willing to retire, as he expressed it, "in the face of the enemy," and would not have it said that he had been driven from his post by any such menaces, and he determined to remain where he was, notwithstanding he received two or three subsequent warnings that his life would surely be taken if he did not depart. Finally, one evening, after he had closed his office, a message was sent to his house that he was wanted there on important business. Not suspecting danger he started to comply with this request. It was then dark. Shortly the report of guns was- heard. Either that evening, or the following morning, his dead body was found beside the road riddled with bullets. He was murdered by the Ku Klux. His remains were sent home, and on their arrival at New York a meeting of a few of his old comrades and friends was held, at which appropriate resolutions were passed. Although he escaped the rebel balls on more than one battle field, he at last fell a victim to rebel hate, which was as unrelenting for years after the war as it was during its progress. He believed that every man was privileged to reside where he pleased, and that, in the South as well as at the North, the right of free speech was not to be abridged or taken away. In seeking to maintain these principles of liberty he died. He was as much a martyr as though he had fallen in full armor, and in the thickest of the fray."
Holbrook, a colonel in the 7th VT, likely knew his brother officer well, and the description of JQD’s ability as an officer and general observations about his personality suggest they derive from personal acquaintance. Certainly, the recollection of JQD’s education and amiability are consistent with the accounts of his friends. Holbrook does not state the source for his account of JQD's post-war career, but a clue is found in his introduction where he thanks the comrades who assisted him in his research. First on his list of acknowledgements is Col. David B. Peck, one of JQD’s closest friends and post-war business partner. Peck’s condolence letter to JQD’s parents suggests that the two men were frequent correspondents. For example, the details about the warning notes must have come from JQD’s letters to Peck.
Holbrook’s reference to the newspaper article is puzzling. JQD wrote sporadically for the Republican Tallahassee Sentinel about politics, usually under a pseudonym. The “article” is probably not an allusion to property auction notices, since I doubt JQD would report to his friends that his role in tax lien sales precipitated threats against him. Nor do we have records of the specific written warnings to JQD to depart to save his life that Holbrook mentions. JQD’s receiving such notes, however, makes sense: Purman reported receiving a warning signed “Ku Klux” as early as the April 1868 and Malachi Martin in Gadsden Co. received similar notices shortly after JQD’s murder.
The assertion that JQD refused to leave Florida in the face of threats, despite the urging of his friends, is entirely consistent with existing correspondence. The detail, however, that on the evening of his death JQD received a note stating he was wanted on important business is startling and confusing. None of the other accounts, including extensive grand jury testimony, mentions such a note. Since JQD was departing his office and was reportedly murdered close to his home, why was this note sent to his house? Could he have arrived home safely and been called out? Frank Bryan, a freedman from Greenwood, was supposedly involved in the murder plot. Could he have been a decoy, delivering such a note to draw Dickinson outside within range of the assassins? (BTW, according to NASA at http://eclipse.gsfc.nasa.gov/phase/phases1801.html the moon was nearly full that night). There is no eyewitness report to account for JQD’s whereabouts between the time he left his office and the discovery of his body, so these possibilities can be entertained, although they change nothing substantive.
And who would have conveyed to Peck the detail about the note on the night of the murder? Maybe A. J. Dickinson, when arriving in Marianna the month after his brother’s death, heard such a rumor and reported it to his family and Peck? Holbrook wrote his account about a decade after JQD’s death, not many years later, so the story of the note may have some basis in reality and not just stem from invented memory. This detail can only be speculated on.
If, for the sake of argument, we believe in the note and accept the implication that the assassination was connected to KKK threats, then John R. Ely is arguably removed as a prime suspect in the murder. The allegation, common in the Jackson Co. black community, that Ely was the murderer stemmed from Ely’s fury over impending auctions of his family’s property. These reports of notes and threats suggest a planned plot, not an impulsive slaying. In fact, Ely vigorously denied (in a remarkably contemptuous and condescending letter to the Tallahassee Floridian) having a hand in JQD’s death. Also, the illiteracy of the Ku Klux note that Malachi Martin received from Jackson County in early 1871 precludes that anyone as eloquent as Ely was involved in such threats. Again all this is idle speculation.
One additional interesting aspect of Holbrook’s account is its decidedly non-reconciliationist tone. In Race and Reunion, David Blight argued that the opposing sides in the war put aside their differences over the war’s causes and emancipation, to fuse a unified American identity (at the expense of African American rights). One aspect of this reconciliation, according to Blight, was northerners conceding to the southern narrative of a cruel and misguided Reconstruction. Holbrook will have none of this. Fifteen years after the close of the war, Holbrook still wrote of “rebels” not former Confederates brother soldiers. Holbrook saw “rebel hate” as “unrelenting” for years after the war as during the conflict itself. Rather remarkably Holbrook portrayed JQD as championing, and the “rebels” as opposing, free speech, the right to live wherever one chose, and the “principles of liberty.” And most stridently, Holbrook declared that JQD’s death in the service of Reconstruction made him just as much a martyr as though he had fallen in the war itself. Granted Holbrook was writing early in the Reconciliation process and this tone would have been more startling years later, but it is noteworthy that Holbrook defied the Reconstruction memory narrative that prevailed for nearly eighty years.