"Here is a breathtaking journey into America's fascinating past, with a man who was there and in the very middle of its magnificent panorama of action," the book's introduction reads.
Keller, who has had three other Civil War books published, said he first got the idea for a Rosser book several years ago when he learned that Douglas Cochran, a retired Hagerstown high school football coach and administrator, was a descendant of Rosser's.
Better yet, Cochran had Rosser's personal account of the Civil War, which was believed to have been clipped from a Charlottesville, Va., newspaper and kept by family members for generations.
Those personal accounts make up the bulk of the 116-page book, which also includes photographs and maps.
"These are his words - the war as he saw it," Keller said.
That meant no editing of text, no matter how long and flowery Rosser's writing got. Keller recalled one particularly lengthy sentence that had more than 150 words.
"We left everything as it was," Keller said.
In many cases, Keller had to add footnotes so readers could better understand what was going on in the war around Rosser.
"Sometimes he wouldn't elaborate on certain events," Keller said.
Maybe because he didn't have any time to do so. Rosser saw action throughout the war, including local battles at Antietam and South Mountain. Often he was victorious in the face of extreme adversity.
"He stuck his nose into tough places. He had no fear at all on the battlefield," Keller said.
Even though Rosser was present when Gen. Robert E. Lee surrendered at Appomattox Courthouse, he eluded the federals and was able to avoid capture for three weeks.