Private JOHN H. McELROY, 16th Reg. of Illinois Volunteer Cavalry

John H.McElroy is believed to have been born c. 1846/47 in Ohio, possibly in Coshocton County. His parents are believed to have been Robert McElroy and Mary (_________) McElroy. His parents are both believed to have died before 1860, leaving John an orphan before the age of 13.
The McElroys may be the family found in Upper, Lawrence County, Ohio at the time of the 1850 census;
Robert A Mcelroy M 28 Pennsylvania
Mary Mcelroy F 26 Ohio
John H Mcelroy M 8 Ohio
Elizabeth Mcelroy F 6 Ohio
Eleta A Mcelroy F 3 Ohio
Cymantha J Mcelroy F 0 Germany

John H. McElroy is believed to be the John H. McElroy who is found residing in York Township, Union County, Ohio at the time of the 1860 census;
Thomas W Miller M 29 Ohio
Mary M Miller F 28 Ohio
Miller O Miller M 1 Ohio
John H Mc Elroy M 13 Ohio

Shortly after this census was taken, John is believed to have struck out on his own, moving to St. Louis, Missouri. After the outbreak of the Civil War, though only 15 years of age, John is believed to have either enlisted or at least aided Union troops that were in the St. Louis area. He then, apparently, moved to Chicago, Illinois, where on March 29, 1863, John H. McElroy lied about his age, claiming he was 20, when he was only 16 to get into the service, so that he could join what would become Troop L of the 16th Regiment of Illinois Volunteer Cavalry.

ILLINOIS STATE ARCHIVES
Illinois Civil War Detail Report

Name MCELROY, JOHN H Rank PVT
Company L Unit 16 IL US CAV

Personal Characteristics
Residence CHICAGO, COOK CO, IL
Age 20 Height 5' 6 Hair DARK
Eyes BLACK Complexion DARK
Marital Status MARRIED Occupation PRINTER
Nativity COSHOCTON CO, OH

Service Record
Joined When MAR 29, 1863
Joined Where CHICAGO, IL
Joined By Whom E A WOLCOTT
Period 3 YRS Muster In APR 16, 1863
Muster In Where CAMP BUTLER, IL
Muster In By Whom
Muster Out
Muster Out Where
Muster Out By Whom
Remarks WAS PRISONER OF WAR PROMOTED REGIMENTAL HOSPITAL STEWARD 2 CLASS SEP 9, 1863

Wikipedia, the free encyclopedia, has the following biography about John McElroy on their site;
"John McElroy (1846–1929) was an American printer, soldier, journalist and author, most known for writing the novel The Red Acorn and the four-volume Andersonville: A Story of Rebel Military Prisons, based upon his lengthy confinement in the Confederate Andersonville prison camp during the American Civil War.
McElroy was born to Robert and Mary Henderson McElroy in Greenup County, Kentucky. When his father died, he traveled to St. Louis to become an apprentice in the printing business.
As a sixteen-year-old in 1863, McElroy enlisted in the Union Army as a private in Company L of the 16th Illinois Cavalry regiment, having earlier served with local Union troops in operations near St. Louis. In January 1864, he was among dozens of men captured in a skirmish near Jonesville, Virginia, by Confederate cavalrymen under William E. Jones. According to his book, Andersonville: A Story of Rebel Military Prisons, McElroy was first sent to Richmond, then to Andersonville in February, 1864. In October, 1864 he was moved to Savannah and within about six weeks was sent to the new prison in Millen, GA (Camp Lawton); thence to several other camps before the war ended.
After the war ended, McElroy was released from captivity and transported back to the North. He settled in Chicago and resumed the printer's trade. He became a local reporter and newspaperman before moving to Toledo, Ohio, to become an editor of the Toledo Blade. He married Elsie Pomeroy of Ottawa, Ohio, and raised a family. In 1879, he wrote Andersonville: A Story of Rebel Military Prisons, a non-fiction work based on his experiences during his fifteen-month incarceration. It quickly became a bestseller and remained popular for the next twenty years.
In 1884, he moved from Toledo to Washington, D.C. to take over as editor and co-owner of the National Tribune. He was active in the local Grand Army of the Republic, serving as commander of the Department of the Potomac in 1896. In 1908, McElroy wrote The Economic Functions of Vice. The following year, he published Struggle for Missouri, a history of the bitter division over slavery that split the state's loyalties and led to armed conflict within its borders. In 1910, he wrote a Civil War novel entitled Si Klegg: His Transformation from a Raw Recruit to a Veteran."

At the time of the 1910 census, John and his family are found in Precinct 3, Washington County, District of Columbia. His father and mother are listed as having been born in New York and Pennsylvania, respectively;
John Mcelroy Head M 66 Kentucky
Elsie P Mcelroy Wife F 67 Ohio
Karl P Mcelroy Son M 43 Ohio

Elsie (Pomeroy) McElroy died on

After Elsie's death, John McElroy was married to Isabel (Worrell) Ball, who was also very active in the G.A.R.