| 1866 | |  Payments to the treasurer, 1866-1867? |
| January | Letter from Patrick Condon to P.J. Downing, January 6, 1866 |
| | Letter from E.L. Patrick to John O'Mahony, January 10, 1866 |
| | Letter from Richard Tobin to B.D. Killian, January 16, 1866 |
| | Letter from John Looby to John O'Mahony, January 22, 1866 |
| | Twenty dollar bond (The Irish Republic), no. 1701, signed by John O'Mahony, January 23, 1866 |
| | Letter from John Mitchel to John O'Mahony, January 27, 1866 |
| | Fenians in Ireland : their hopes and fears ... (The New York Daily Tribune, January 28, 1866) |
| | Fifty dollar bond (The Irish Republic), no. 709, signed by John O'Mahony, January 31, 1866 |
| February | Letter from William J. Nagle to E. Murray, February 2, 1866 |
| | Ten dollar bond, no. 535, issued to Denis Fitzgerald, Brooklyn, New York, February 5, 1866 |
| | Letter from Patrick Condon to Thomas Mulcahy, February 14, 1866 |
| | Letter from John Mitchel to M. Moynahan, February 19, 1866 |
| | Clipping entitled "Important Letters from John Mitchel and James Stephens" with introduction by P.J. Downing dated February 20, 1866 |
| | Letter from Thomas Siske to B.D. Killian, February 20, 1866 |
| | Letter from P.A. Collins (Secretary Treasurer, Fenian Brotherhood, New York, N.Y.) to the District Centres, Centres, and members of the District of Manhattan, February 21, 1866 |
| | Letter from John Hasson to John O'Mahony, February 23, 1866 |
| | Letter from Martin O'Brien to John O'Mahony, February 23, 1866 |
| | Letter from Patrick Condon to P.J. Downing, February 25, 1866 |
| March | Letter from John Hasson to P.H. Connor, March 1, 1866 |
| | Ten dollar bond, no. 763, issued to John Mulcahy, Charleston, March 2, 1866 |
| | Twenty dollar bond, no. 1499, issued to Laurence Madden, March 5, 1866 |
| | Ten dollar bond (The Irish Republic), no. 1803, signed by John O'Mahony, March 5, 1866 |
| | Twenty dollar bond (The Irish Republic), no. 1686, signed by John O'Mahony, March 10, 1866 |
| | Letter from John Mitchel to John O'Mahony, March 10, 1866 |
| | Letter from Patrick O'Brien to R.M. Hodgsden, March 12, 1866 |
| | Report of the Daniel O'Connell Circle, Fenian Brotherhood, March 24, 1866 |
| | Ten dollar bond (The Irish Republic), no. 1579, signed by John O'Mahony, March 26, 1866 |
| | Letter from Laurence Reynolds to Denis Downing, March 28, 1866 |
| | Letter from Thomas Egan, March 30, 1866 |
| | Letter from Patrick Condon to P.J. Downing, March 31, 1866 |
| April | Letter from William M. Griffin to John O'Mahony, April 4, 1866 |
| | Letter from John Mitchel to John O'Mahony, April 7, 1866 |
| | Letter from John Mitchel to John O'Mahony with enclosure, April 7, 1866 |
| | Letter from John Mitchel to John O'Mahony, April 10, 1866 |
| | Letter from James I. Hayes to Col. Jno. G. Healy, April 17, 1866 |
| | Letter from James Stephens to "My Dear Friend", April 26, 1866 |
| | Letter from Patrick J. Hickey to John O'Mahony, April 29, 1866 |
| | Letter from Hugh Cunningham to William M. Griffin, April 30, 1866 |
| | Letter from Patrick Condon to P.J. Downing, April 30, 1866 |
| July | Letter from John D. Nolan to James Stephens, July 4, 1866 |
| | Letter from James Ryan to P.A. Collins, July 26, 1866 |
| August | Letter from Patrick Condon to T.J. Kelly, August 13, 1866 |
| | Letter from R.W. Dowling to T.J. Kelly, August 25, 1866 |
| | Letter from Edward J. Comerford to T.J. Kelly, August 27, 1866 |
| | Letter from "Treasurer" - Margaret O'Connell to T.J. Kelly , August 31, 1866 |
| September | Letter from James Steele (James Stephens) to "Dear Friends", September 12, 1866 |
| | Letter from William J. Nicholson to James Stephens, September 20, 1866 |
| | Letter from Thomas H. Hall to T.J. Kelly, September 25, 1866 |
| | Letter from Hugh Cunningham to T.J. Kelly, September 26, 1866 |
| October | Letter from "A Southern Fenian Informant" to James Stephens, October 20, 1866 |
| | Letter from Michael Printhers to T.J. Kelly, October 20, 1866 |
| November | Letter from William J. Nicholson to T.J. Kelly, November 7, 1866 |
| | Letter from Edward J. Comerford to D. O'Sullivan, November 8, 1866 |
| | Letter from John Mitchel to M. Moynahan, November 17, 1866 |
| December | Letter from John Warren, December, no day, 1866 |
