A little-known diary of invalid teenager LeRoy Wiley Gresham, who chronicled the Civil War, and his own ailments, from his home in Macon, Ga. (Michael Ruane/The Washington Post)

Mary Baxter Gresham was 42 when her invalid son, LeRoy, died in June 1865.

She had already lost two infant children and had just lived through the upheaval of the Civil War in Macon, Ga.

But when 17-year-old LeRoy, know as “Loy,” died on June 18 in the house where he was born, she was devastated.

“God has tried me often and in many ways but never has my heart been so wrung as now,” she wrote to her sister, Sallie, on July 12. “And yet the trial had so much mercy mixed with it that my soul swells within me when I think it all over.”

Last week, Mary Gresham’s moving letter was posted online by the Library of Congress, along with her son’s extraordinary seven-volume, five-year journal.

LeRoy Wiley Gresham (Library of Congress)

The Library featured selected pages from the little-known diary in a Civil War sesquicentennial exhibit in 2012 and 2013 and has since had it, along with some family correspondence, prepared for the Internet.

The diary, which the Library thinks has never been published, is a fascinating look at the war through the eyes of a precocious Southern youngster who was largely housebound by illness.

He had a host of afflictions that appeared to stem from an improperly healed broken leg, which was “drawn up” and useless.

It is also a portrait of a well-to-do, slave-owning household, its family and slave dynamic, and the infirmities that tormented the frail author up to his death.

Mary Gresham’s letter, which the Library thinks has never before appeared in a public forum, is a voice from outside the journal.

She is simply “Mother” in her son’s narrative — making periodic appearances, at one point because she dropped him while carrying him around the house. He weighed 63 pounds.

She is the offstage presence but has been watching her son’s deteriorating health and approaching death.

LeRoy Wiley Gresham was 17 when he died in June 1865. (Michael Ruane/The Washington Post)

She and her husband, John, a local politician, businessman and plantation owner, had two other children — a younger daughter, Minnie, and an older son, Thomas.

The family had 51 slaves, eight at its elegant Greek revival home on College Street and 43 on its nearby plantation, according to the Library. (The Gresham home still exists in Macon as an inn.)

The letter is a window into a bygone era and a timeless epistle from a grieving parent.

“Mrs. Gresham’s deep grief at the loss of her son is so palpable on every page,” Michelle A. Krowl, Civil War and Reconstruction specialist at the Library, wrote in an e-mail. “Her heartbreak is familiar to anyone who has lost a loved one, and the pain she expresses cuts across the centuries.”

The eight-page letter opens:

“I will try to write to you my dear sister, though when I attempt to put on paper anything of my departed treasure’s last days I feel it so poor and cold compared with the emotions of my aching heart, that for a sense of duty I would not write at all.”

LeRoy had been disabled for years and suffered from what appeared to be painful bedsores, as well as a chronic cough. His health was a roller coaster of illness, recovery and relapse.

His began his diary in June 1860, when he was 13. His final entry was June 9, 1865, two months after the close of the war and nine days before he died.

His mother described his final hours.

“I had for some days lost hope, but would not give way for fear of trying him, for watchful to the last, he was quick to see any sign of grief upon my face (and) racked with suffering as he was, his ready sympathy was for me (and) for us all,” she wrote.

“The day before he left us, while Mr. G. and the children were at dinner, he suddenly said to me . . . ‘Mother this is the end.’ I said ‘What do you mean my son.’ ‘I am dying ain’t I,’ was his reply. Oh my God I thank thee for the strength given me then . . .

“He had suffered so much from nausea during the last week that his countenance had a look of distress which I never saw . . . before,” she wrote. “And his tongue was so sore and stiff that it was painful to speak . . .

“It had been our dread to see him struggle or strangle in coughing, but God dealt mercifully with him and us. For his departure was so quiet that we watched to see him breathe again, and his face assumed in death the quiet serenity habitual to it in life . . .

“I could scarce tear myself away from his precious body, it was so sweet and peaceful,” she wrote. “How am I to live without him who has been the star of my life (and) my heart’s delight for 17 yrs.”

She told her sister that she, her husband and son, Thomas, washed and dressed LeRoy’s body for burial.

In an aside, she expressed bitterness that none of the family’s slaves, “who professed to love him,” paid their respects. “God forgive them,” she wrote. “I humbly hope that I may never see them again.”

But, as LeRoy had noted in his diary, with the end of the war and slavery, most of the family’s “servants” had embraced their freedom and left.

“The same loving hands that ministered to him in life performed the last duties,” his mother wrote. “Those who bore him away from the house consecrated by his birth, life and death were just such as he would have preferred.”

She added, “The Saviour took him from our arms and now no more pain, no days of weariness, and nights of wakefulness, no more sighing and longing for rest.”

Below the last entry in LeRoy’s journal, someone else, perhaps his mother, wrote: “(LeRoy Wiley Gresham, author of this diary, died in Macon. Ga. June 18th 1865.)”

Twenty-four years later, in 1889, Mary Gresham died at the age of 66. She was buried in Macon’s Rose Hill Cemetery beside the grave of her son.