His death was "deeply mourned" by many, according to historian Luther Reily Kelker, who said of Egle, "few brighter, nobler types of manhood have ever adorned the generations of men in the Keystone State.

Reared in Dauphin County, Pennsylvania, he was compelled to relocate to the home of his paternal grandmother in 1834, following the sudden death of his father.

Supporting his training through employment as a teacher and mail clerk, he enrolled in 1857 for formal studies with the medical department at the University of Pennsylvania, graduating from there in March 1859.

Stationed in Virginia with his regiment throughout the fall of 1862, he experienced his first true taste of life as a combat surgeon with the 96th Pennsylvania's participation in the Battle of Fredericksburg.

Involved in engagements ranging from light skirmishes to intense battles under heavy rifle and artillery fire beginning on December 12, 1862, he and his fellow 96th Pennsylvanians finally found relief three days later when they were ordered back across the Rappahannock River and made camp near White Oak Church.

When the threat was deemed over by Pennsylvania's governor and senior military leaders, these units were disbanded, and their men were sent back to their respective communities.)

"[12] This triumph was soon followed by tragedy, however, when Egle learned that his only son, Beverly, had died suddenly in Cook County, Illinois on June 21, 1882.

[13] In addition to his work as an author and historian during the early to mid-1880s, William Egle was also employed as the physician for Dauphin County's prison.

Dr. George Edward Reed, the head of Dickinson College in Carlisle, Pennsylvania,[17] Egle was described as a physician shortly after the turn of the century, when a federal government employee arrived at his Harrisburg home to interview him for the 1900 U.S. Census.

[1][19] In the days following his death, The Harrisburg Patriot described him as "a noted physician, historian and genealogist and the author of a large number of valuable works of local and national interest.

In a "this day in history" chronology presented in its September 17, 1908 edition, the daily newspaper of Palestine, Texas listed the birth of "William Henry Egle, historian" as its noteworthy event for the year 1830.