More than 150 years later, the world can now view the conflict through his eyes.
LeRoy Wiley Gresham wrote his personal observations nearly every day from June 1860 until he died June 18, 1865.
He gleaned what he could from letters, conversations and newspapers.
Gresham's 700 pages in seven volumes are now a star attraction of "The Civil War in America" display at the Library of Congress in Washington, D.C.
"His diary gives you somewhat of a 'You are there' quality," said Michelle Krowl, the Civil War and Reconstruction specialist for the Library of Congress. "He's doing all this in a very literate, learned style. His spelling is wonderful, his sentences are complete, and he's a very thoughtful diarist."
Gresham died at age 17, about two months after Confederate Gen. Robert E. Lee's surrender at Appomattox Courthouse in Virginia.
In the exhibit, his writings are open to November 1864, when the Gresham family is trying to decide whether to flee their home.
From atop the family mansion, now the 1842 Inn, he could see battle fires blazing in the distance as Gen. William T. Sherman's troops moved closer.
"Residents of Macon are not sure which direction Sherman's armies are going to take once they leave Atlanta, so there's a lot of anxiety and consternation that perhaps Macon is the next intended target," Krowl said.
LeRoy's father, John J. Gresham, twice mayor of Macon, had already left to fetch another son, Thomas, who was fighting in Virginia in the $500 Confederate uniform the family bought for him.
LeRoy and his mother stayed, but his younger sister Minnie joined other refugees leaving town.
She would later marry wealthy Baltimore businessman Arthur Webster Machen, whose family preserved the diary and other Civil War era papers that were donated to the Library of Congress in 1984.
More than 200 other items are on display in the exhibit that runs through June 1, 2013, but LeRoy's unpublished writings stand out — along with an ambrotype image of him.
His neat penmanship and colorful depictions of Southern life caught the eye of Washington Post writer Michael Ruane. The journalist of 40-plus years read every word, something Krowl still plans to do.
Ruane's story on the diary has drawn more attention to LeRoy's writings.
As a writer, Ruane was struck by the boy's impeccable spelling — only the word "guard" was misspelled. Each reference consistently transposed the "u'' and the "a," Ruane said.
"His grammar, spelling and syntax are superb," Ruane said. "I thought it was absolutely superb his choice of words."
Ruane, who hails from Philadelphia, learned a few new words of his own such as syllabub, a traditional English dessert, and scuppernong, a large variety of muscadine grapes native to the South.
Ruane begins his article on the diary by calling attention to smudges from LeRoy's sweat falling onto an entry from July 1862.
"He tried to rub them off, but they smeared the ink," Ruane wrote.
He noted the young man's explanation to future readers of the "terribly hot" conditions.
Ruane was fascinated by the slice of Southern life LeRoy served up from a position of privilege and torment, due to his drawn-up broken leg and the countless remedies of opiates and poison he endured.
"I was somewhat stunned at the amount of drugs he took, not nefarious, but the top medical treatments of the day," Ruane said.
Readers learn how LeRoy found relief from the heat with watermelon chilled from a dip down the well.
The dated entries nearly always begin with a note about the weather, Krowl said.
"He's a wonderful observer," she said.
His insight gives a clear picture of how the fighting impacted his community and immediate family.
Tidbits of letters from his soldier brother and others tell tales from the front lines.
The young Gresham seemed to thrive on any news of the war. Confined to a mattress in a wagon drawn by slaves, he soaked up all the scintillating details.
"You know what he's witnessing firsthand from Macon, what people are telling him, what news he's receiving from elsewhere in the war and also the newspaper reports he's receiving," Krowl said.
On Nov. 17, 1864, he penned news of a letter detailing Sherman's progress moving south of Atlanta and what he saw during a trip to the doctor: "Found the town in an uproar about the approach of the enemy, who are this side of Griffin and 'marching on,' 10 & some declare 15,000 strong."
The teen was highly educated and well-versed in classic literature from the work of Charles Dickens to Charlotte Brontë's "Jane Eyre."
"That's why we're so enthralled with this diary," Krowl said. "You pick almost any entry and he says something interesting about the war, or Macon or what his family is going through."
The Greshams were prosperous but not immune to the shortages of war. As paper became scarce, LeRoy had to scrounge in the family library for blank sheets to maintain his daily journal.
Ruane noted the teen's unfailing, passionate support of the Confederacy, even when other family members lost sight of victory.
"His father is a sensible guy and sees the handwriting on the wall," he said.
The elder Gresham practiced law, served as a judge and was elected mayor in 1843 and 1847.
In 1849, he became president of the Macon Manufacturing Co., which built the city's first cotton factory, a precursor to the old Bibb mill on First Street, according to the archives at the Washington Memorial Library.
Upon his death in 1891, The Telegraph reported "Macon's most useful citizen and benefactor" would be laid to rest days later.
Schools closed in the city. In Athens, the campus shut down at the University of Georgia, where Gresham had served as a trustee for 20 years.
"No funeral ceremonies ever conducted in Macon were more impressive and never did Macon's citizens of high and low degree attend in such numbers to pay a last tribute to the dead," the report in The Telegraph read.
The family burial plot anchors a corner of the Magnolia Ridge section overlooking the Ocmulgee River at Rose Hill Cemetery.
Towering Celtic crosses rise like chess pieces on the graves of LeRoy's parents.
His marble monument stands between them and two of his brothers. Edmund died in infancy before LeRoy was born and Edward Tracy, LeRoy's younger brother, died at age 6 when LeRoy was 11.
The family's love for the teen diarist is evident in his epitaph:
"In life this dear child was the light of the home circle, lovely and endearing by nature he was purified by suffering, sanctified by grace and rests now in the bosom of his Savior. Blessed are the pure in heart for they shall see God."
Because of his physical limitations, LeRoy was often confined to the first floor of the home.
"As people came in and out of the house, he's the one that they tell things to because he's always there," Krowl said. "He's that sort of lodestone for the family."
Penning his thoughts and feelings seemed to offset his constant pain and discomfort, Krawl said.
With news traveling slowly from battlefronts, LeRoy devoured newspapers from Richmond, Va., Memphis, Tenn., and daily copies of The Telegraph.
After documenting a Confederate victory at Gettysburg, he later made a correction.
"He goes back and slips in a blue piece of paper to rectify that when he's finally hearing the outcome of the battle," Krowl said.
Ruane also found snippets of cloth and an insect wing pressed between the pages.
He finds fascinating the attention LeRoy paid to make sure the record is straight.
It would take days, too, before the young Gresham learned of the surrender at Appomattox.
LeRoy lamented the departure of slaves at the end of the war as his health took a final turn for the worst.
"It's clear to me he has some affection for these people," Ruane said.
The family hired two devoted servants after their emancipation, he said.
In the last complete entry, LeRoy bewailed that he may never see again his "valet" Bill.
Ten days later, the teen died, but his story lives on in the newly explored diary.
Many attending the exhibit have come in looking for the young man they read about in the newspaper, Krowl said.
"Oh, this is the boy from the Post," she's overheard in the gallery.
They are excited to see his image on glass encased in an ornate gold-trimmed cover.
His light-colored eyes are now windows for all to look into a dark time in U.S. history.
"You really see the whole war play out in the pages," Ruane said.