Lawyer who served in Lincoln’s cabinet as postmaster general (1813–1883). Civil War–dated DS, signed “Yrs respectfully, M. Blair, Pm G, Wash’n Sept. 8th 1864,” one page, 5 x 8, August 25, 1864. Blair signs at the conclusion of an autograph request document issued by the Western Illinois Sanitary Fair Committee. In part: “As a means for increasing the fund for the benefit of our soldiers, and procuring a valuable and interesting collection, the Executive Committee have decided to respectfully request the Autographs of prominent persons.” In fine condition. Accompanied by an unsigned original carte-de-visite portrait of Blair. RR Auction COA.