The Confederate soldier stopped at a blacksmith shop to get his horse's shoe replaced and made the mistake of bragging about how he and his Rebel calvary buddies burned and looted Chambersburg that day. It was his last mistake.
"The blacksmith 'brained' him with his hammer," Alexander said.
Several Confederate soldiers died that day. A Captain Bailey was drunk on some looted whiskey and got separated from his unit, Alexander said. He was felled upon by an angry mob of Chambersburg citizens who had watched as their town was burned.
Two brigades of Confederate cavalry under the command of "Tiger John" McCausland took only a few hours to burn down the Franklin County Courthouse on the public square and the core of what then was downtown Chambersburg, Alexander said in the new book, "History and Tour Guide of the Burning of Chambersburg and McCausland's Raid."
More than 500 homes and businesses were destroyed by the fires that left more than 2,000 people homeless. Damage was estimated at more than $1 million in 1864 dollars, he said.
The raid was ordered by Confederate Gen. Jubal Early in retaliation for the depredation that Union troops were doing in Virginia's Shenandoah Valley, Alexander said.
The book, which came out late last year, is an offshoot of Alexander's master's degree thesis from the University of Maryland, written in 1987.
Its centerpiece shows New York artist Ron Lesser's painting of the burning of Chambersburg.
The book was published as a combined project between Blue & Gray magazine, a Civil War periodical, and the Chambersburg Heritage Center, a historical interpretive center. It can be bought at the center for $9.95 or at the visitors center at Antietam National Battlefield for $12.
It details how 2,800 rebel cavalry left the area around Hedgesville, W.Va., and rode north through Mercersburg, Pa., then east along what today is U.S. 30 to Chambersburg.
Early set other Rebel units out on diversionary raids to fool the Yankees while McCausland headed for Chambersburg and the real objective.
"In Chambersburg, the early morning calm was broken around 5:30 a.m. by the belching of Confederate cannon.
"About a half-dozen rounds were fired over the town. Residents who peeped out of their windows saw Confederate cavalry lined up on Fairground Hill west of town. At the same time men of the 8th and 36th Virginia were sent into town on foot to reconnoiter, followed by (Maj. Harry) Gilmore's Maryland cavalry to assist in blocking exits."
"The citizens thought it was only a bluff," Alexander said.
Alexander comes to Civil War history by way of family. He had ancestors on both sides in the war, he said.
Alexander's father was from Mississippi and his mother grew up and still lives in Greencastle. They met during World War II, when his father was assigned to Fort Ritchie, he said.
Alexander was born in Mississippi in 1949. His father died from a brain tumor when Alexander was only a few weeks old. His mother returned with him to Greencastle.
"I was raised by an extended family - grandparents, aunts and uncles," he said.
His first taste of Civil War history came at age 5, when his mother took him to Gettysburg, Pa.
"That's when I got the bug on this," he said.
Alexander graduated from Smithsburg High School, served in the Marine Corps, including a tour in Vietnam, and earned his bachelor's and master's degrees in history from the University of Maryland.
He taught U.S. history to ninth-graders in Greencastle for two years, then took a part-time job with the National Park Service at Harpers Ferry (W.Va.) National Historical Park as an interpretive park ranger.
He went full time with the park service and worked in Washington, D.C., in 1982. He was assigned to Antietam in 1985, first as a park ranger, then volunteer coordinator. He was promoted to staff historian in 1992.
Alexander runs the park's library, does research, writes historical reports, coordinates special programs and manages the park's museum and archives.
Alexander writes a regular column for the Echo Pilot, a weekly newspaper in Greencastle, and conducts study tours for the Smithsonian Associates.