"I declined for want of time and strength to lift him," Freeman wrote a few days later in a letter home.
Then the officer asked Freeman to take his handkerchief and wipe the sweat from around his eyes. Freeman, still under fire, did.
"When exposed in this way to the hot sun and the perspiration starting out freely, it will soon form quite a thick crust and unless wiped from the neighborhood of the eyes it soon becomes very painful," the young sergeant wrote his father.
Three days of fighting in July 1863 in the Pennsylvania countryside left more than 50,000 soldiers dead, wounded, captured or missing.
Freeman survived Gettysburg. It was his ninth battle, from the second Battle of Bull Run in Virginia in 1862 to the struggle for Richmond near the end of the war, fought from 1861 to 1865.
His accounts made him the favorite Civil War chronicler for Margaret E. Wagner, a senior writer and editor at the Library of Congress.
Wagner's new volume, "The American Civil War: 365 Days," has nearly 500 photographs, lithograph, paintings, drawings and cartoons from the hundreds of thousands in the library's keeping.
Many are rarely seen and some may never have been published, Wagner said.
One photo, showing Freeman in uniform, is the frontispiece of a book published six years after the war — "Letters from Two Brothers Serving in the War for the Union to their Family at Home in West Cambridge, Mass." Eugene Freeman was an engineer in the Union Army's transport service; Warren served in the 13th Massachusetts Volunteers.
"I don't know what happened to him after that," said Wagner, who quotes from him repeatedly in her book.
She also cites the diary of Col. John Beatty — later a brigadier general for the Union side — who was angry at what seemed to be attacks by civilians in Alabama.
"I told them that bushwhacking must cease," Beatty wrote. "Hereafter every time the telegraph wire was cut we would burn a house and every time a train was fired upon we would hang a man, and we would continue to do this until every house was burned and every man hanged between Decatur and Bridgeport" — a distance of 77 miles.
The pictures in Wagner's book do not spare the sensibilities of viewers:
Another of Warren Freeman's letters say it was both strange and painful that death was mentioned so little in the army.
"I remember one of our boys — he was in the same mess with me; he used to speak of some statistics of other wars, how many pounds of lead and iron it took to kill a man and how few were killed in proportion to the number engaged, and what a good chance there was to get off whole — his name was Henry Holden, and he was the first man killed in my company at (the second battle of) Bull Run," the Union sergeant wrote.
Wagner was the co-author and co-editor of "The Library of Congress Civil War Desk Reference" in 2002. Her book is published jointly by the library and Harry N. Abrams Inc.