Nowadays, the word deadline is used all but exclusively to refer to a date or time by which something must be accomplished. But over the centuries, the term has been used in a number of different contexts: Among early 20th-century printers, for instance, a deadline was a line marked on a cylindrical press outside of which text would be illegible, while the Oxford English Dictionary has unearthed a reference to an angler’s “dead-line” dating from the mid-1800s referring to a weighted fishing line that does not move in the water.

The modern sense of deadline, however, may be influenced by a much more dangerous meaning. It originated during the Civil War, and came to prominence during the much-hyped trial of an infamous Swiss-born Confederate leader named Henry Wirz.

Wirz was born Heinrich Hartmann Wirz in Zürich in 1823. In his early twenties, a court forced him to leave Zürich for 12 years after he failed to repay borrowed money, and in 1848 he left first for Russia before eventually settling in America. After working a string of jobs at several spots around the country, Wirz married a woman named Elizabeth Wolf in 1854 and moved to Louisiana. After the outbreak of the Civil War in 1861, he enlisted as a private in the Fourth Louisiana Infantry.

One of Wirz’s first engagements in the war was the Battle of Seven Pines on May 31, 1862. He was badly wounded in the fighting, losing the use of his right arm, and when he returned to his unit a few weeks later he was promoted to the rank of captain in recognition of his bravery and service. From there, Wirz rose through the ranks to become an adjutant to John H. Winder, an experienced and high-ranking general overseeing the treatment of Confederate deserters and Union prisoners. In 1864, Wirz was put in control of Camp Sumter, a newly-established internment camp for Union soldiers located near Andersonville in rural Georgia.

Over the remaining 14 months of the war, Camp Sumter grew to become one of the largest prisoner of war camps in the entire Confederacy. At its peak, it held more than 30,000 Union prisoners, all of whom shared an enormous 16.5-acre open-air paddock—conditions inside of which were notoriously grim. Disease and malnutrition were rife, and a lack of clean water, warm clothing, and adequate sanitation led to the deaths of many of the camp’s prisoners. Of the 45,000 Union prisoners held in the Camp at one time or another, it is estimated that almost a third succumbed to Sumter’s squalid and inhumane conditions.

In his defense, Wirz later claimed to have had little real control over the conditions in the camp, and it is certainly true that the day-to-day running of Camp Sumter was a disorganized affair divided among numerous different parties. Incompetence, rather than malice, may have been the cause of many of the camp's horrors.

Execution of Captain Henry Wirz in 1865 Library of Congress

In 1865, the war came to an end and Wirz was arrested in Andersonville. He was eventually sent to Washington, and held in the Old Capitol Prison to await trial before a military commission. That fall, more than 150 witnesses—including one of Wirz’s own prison staff and several former prisoners—took to the stand and gave testimony. Many provided damning evidence of Wirz’s harsh treatment of the prisoners (although historians now think some of these testimonies were exaggerated). As accounts of him withholding food and other supplies from prisoners found to have committed even minor offenses were relayed in the press—and as the full extent of the terrible conditions inside Camp Sumter became public—Wirz emerged as a much-vilified symbol of the camp’s inhumane treatment of its Union prisoners.

One of most damning examples of his inhumanity was his implementation of what became known as the Camp’s dead line:

Wirz, still wickedly pursuing his evil purpose, did establish and cause to be designated within the prison enclosure … a “dead line,” being a line around the inner face of the stockade or wall enclosing said prison, and about twenty feet distant and within said stockade; and so established said dead line, which was in many places an imaginary line, in many other places marked by insecure and shifting strips of [boards nailed] upon the tops of small and insecure stakes or posts, he … instructed the prison guard stationed around the top of said stockade to fire upon and kill any of the prisoners aforesaid who might touch, fall upon, pass over or under or across the said “dead line” ... —Report of the Secretary of War, October 1865

In other words, this deadliest of all deadlines was a line Wirz implemented just inside the inner wall of Camp Sumter. Any prisoner wandering beyond the line would immediately be killed.

Stories like this were all the evidence the court needed: Wirz was found guilty of violating the rights of wartime prisoners, and was hanged on the morning of November 10, 1865.

Widespread press reports of Wirz’s trial and the horrors of Camp Sumter soon led to the word deadline being popularized, and eventually it passed into everyday use—thankfully in a less severe sense.

By the early 20th century, the word’s military connotations had all but disappeared and the familiar meaning of the deadlines we meet—or miss—today emerged by the early 1920s.