The Isaac Best manuscripts were prepared in the 1880s or 1890s for the veterans organizations of the 16th and 121st New York Infantry Regiments. These include three extended essays, "Sheridan in the Shenandoah" (F6:1a), "The Siege and Capture of Petersburg" (F6.1b), and "Through the Wilderness with Grant" (F6.1c).
These essays are clearly-written post-war reminiscences in the grand old style of the Grand Army of the Republic, and contain both personal, anecdotal information about the incidents gathered first-hand, and information undoubtedly gathered from secondary sources. They focus on the critical campaigns of the spring and summer of 1864, after the arrival of Ulysses S. Grant both bathed the soldiers in blood and revitalized the hopes of the Army of the Potomac.
"Sheridan in the Shenandoah" includes a rapid, second-hand narrative of the struggle for the Valley in 1862 and 1863, and Best's personal recollections of the fall campaign of 1864. Particularly noteworthy are his accounts of the 3rd Battle of Winchester and Fisher's Hill, and a very detailed account of Cedar Creek. As an aside, Best comments that the importance of "Sheridan's Ride" has been much overplayed, and argues that much of VI Corps was not in flight and had never been broken at all. While he reserves praise for Sheridan, he argues that the emphasis on the importance of the ride robbed Gen. Horatio Wright of his due. Best also offers his analysis on the role of morale in shoring up the efforts of the armies.
"The Siege and Capture of Petersburg" is an attempt at a comprehensive retelling of the major events of the siege of Petersburg from the end of the Battle of Cold Harbor through the end of the war. Best witnessed the long, drawn-out battles in front of Petersburg during the summer of 1864, including the disaster at the Crater, and the several attempts to circumvent the Confederate defenses during the following winter. In 1865, it appears that Best was assigned to Sheridan's command during his final raid into Northern Virginia.
The essay "Through the Wilderness with Grant" includes detailed accounts of the Battle of the Wilderness, Spotsylvania, North Anna River, and Cold Harbor, nearly all written from Best's recollections, including seeing several close friends killed. The end of the essay includes a generally positive appraisal of Grant's strategy.