I am sure that somebody in this sub could recommend a definitive biography on John Brown however I enjoyed this book: Evan Carton (2006). Patriotic Treason: John Brown and the Soul of America.

The memoirs of Sherman are fantastic, if dry, as you might expect from a memoir written in the 19th century. Some of it deals with battle formations (if you're a military historian, may prove interesting, but not for me personally).

My personal favorite parts of the memoirs are where he lists transcripts of letters between himself and others - him and Grant did not see eye to eye on a lot of things, to say the least.

You can actually read it online via Project Gutenberg, if you like: http://www.gutenberg.org/files/4361/4361-h/4361-h.htm

Although they don't cover John Brown all that much, Bruce Catton's two-part exploration of U.S. Grant ('Grant Moves South' & 'Grant Takes Command') provide some spectacular insight into the western theater of the ACW, and shed a lot of light on Sherman as both a general, and friend of Grant. In particular, Catton lays out how Grant's final expedition to take Vicksburg was a massive influence on Sherman's eventual march through Georgia and South Carolina.

In brief, Grant had organized several different expeditions and attack plans to take Vicksburg (straight across the Mississippi, down the Yazoo, digging a separate river channel, etc.), but finally came to the idea that the best way to do it was to unhook from his supply lines, march well south of Vicksburg through the bogs and swamps (where the supply trains couldn't follow), cross the Mississippi, and live off the land as he went. Grant (correctly) predicted that with light rations, his men would be able to survive off of southern spoils, which would simultaneously feed his army whilst robbing the southern armies of their potential supplies. It also allowed his army to move fast, and to potentially surprise his opponents. It worked, and Grant was able to maneuver around to take Jackson (a main supply hub for Vicksburg) and invest around Vicksburg before Joe Johnston could get there to help out. Ironically, Sherman thought Grant was crazy to try this (abandoning one's supply lines was thought to be suicide in enemy territory), but eventually came to see the genius of the plan. As fate would have it, Sherman made his name in American history for his "March to the Sea," which was essentially an expanded version of that same theory he'd thought was so foolhardy!

Not my flair area, but I enjoyed Tony Horwitz' Midnight Rising: John Brown and the Raid That Sparked the Civil War. Henry Holt. 2011. ISBN 978-0-8050-9153-3. It's the author who wrote Confederates in the Attic.