As words turned to action leading to the (American) Civil War, few could foresee the violence, scope, or length of time the war would last. Both sides (North and South) were relatively unorganized and not prepared for the war which would follow. This included the use of espionage and intelligence. The Civil War was a breeding ground for advancement of technique and technologies used for espionage and intelligence. Without such a war these inventions and technologies would be prolonged in invention. Innovation stemmed from necessity, the war created the necessity.

The Civil War started just after the election of Abraham Lincoln in 1860. One month later South Carolina seceded from the Union. The South was prepared to take Fort Sumter from the North. Lincoln sent a naval squadron to Fort Sumter, thus signaling South Carolina that it was their decision on when to start the war. South Carolina attacked the Union forces at Sumter on April 12th 1861 at 4:30 a.m., thus starting the Civil War, taking people by surprise, despite their knowledge of an impending war. However, this was a different war then America had ever fought. New inventions that changed war. The telegraph, the use of roads, and rail allowed armies and strategies to change at an unprecedented pace. Both sides soon learned that military intelligence would be their biggest asset. After the Civil War intelligence was higher on the agenda.


During the war there where two terms used for a person spying. One was simply spy and the other was scout. The simple difference between the two was just a distinction between the garb. If one was wearing the uniform of his side then it was a scout. If the person was wearing a uniform of the enemy or in plain clothes it was considered spying. During the Civil War many spies where civilians, and were therefore not permitted to wear a uniform. The Civil War was a war of strong loyalties and passions which sometimes even divided neighbors. Thus, it was not hard to find volunteers for spying. Many of the spies were simply civilians who were in the right place at the right time. They might have heard something and then told a local commander. Although spies were important there was no one spy who shined above another, nor was spying the only form of intelligence used. The act of spying was not yet refined. Many Generals, including Lee, employed the use of Calvary for reconnaissance. Other methods used by Lee for obtaining information were wiretapping and communication intelligence balloons. Some armies had scouts on high mountains to see the oncoming armies. Interrogation of prisoners was another method for intelligence gathering.

The Confederates needed to know where the Union’s armies would strike next so they could bring men to defend. The Union needed to know what was waiting for them in the town they were preparing to invade, as well as the strategy of the Confederates, so as not to be caught in a trap.

Secret Service

One myth about the Civil War was that both sides had a “Secret Service,” or a centralized spy agency run by the government for the whole the military's sake. This is not true. However, some generals did hire detectives, such as George B. McClellan, who hired Allan Pinkerton, but many went without the help of espionage. Although one detective, Col. Lafayette C. Baker, was believed to be in charge of a beginning stage of a Secret Service, his agency was only concerned with capturing Confederate spies. The phrase “Secret Service” did not contain as much prestige and awe back then. This is obvious because the phrase was used for many intelligence bureaus. One of the South's intelligence divisions used official-looking stationary that bore a letterhead proclaiming the “Secret Service Bureau” The North also formed poorly coordinated, quasi-official groups, including one grandiosely dubbed the National Detective Police- though it mustered, at maximum, about thirty men. Through creating many different bureaus for intelligence gathering, there was a lot of trial and error. This system helped refine espionage and intelligence gathering to what it is thought of today.

There where no standard guidelines on how intelligence was processed. In some cases it was assigned to the “Provost Marshal.” other times it was assigned to the signal officer, or even the General. For instance when Union general Greenville M. Dodge took personal responsibility with the intelligence. He even went so far as to supervise the work of his scouts.

The most professional Secret Service of the Civil War was the Union’s Bureau of Military Information (military information being the term used for military intelligence during the Civil War). The BMI was established by Col. George H. Sharpe at the command of General Joseph Hooker when he became commander of the Union’s army of the Potomac in January 1863 . The BMI didn’t start to have an army wide popularity until 1864 when Sharpe was promoted to General-in-Chief Ulysses S. Grant’s intelligence officer. This added another successful example after which to mold espionage and intelligence gathering.

Confederates in Canada

In 1864, after many failures, including Gettysburg, the Confederates began to rely more heavily on covert actions. One such operation was executed by Jacob Thompson, a Confederate leader, who was sent to Toronto, Canada where he began economical and psychological procedures against the Union. He was in command of a massive covert operation code-named the Northwest Conspiracy. The object of the Northwest Conspiracy was to separate several Northern border states from the Union and establish them as the Northwest Confederacy, and release Confederate POWs in Illinois and Ohio. The separated states would become allies with the South, thus sandwiching the Union. The end result of the Northwest Conspiracy was the burning of many buildings, and the robbery of a couple of banks in Vermont. These results were a far cry from the objectives of the Northwest Conspiracy. The South learned from this that espionage is not a concrete art of war.

Before the Civil War had even begun, an attempt, unannounced to the Confederate leaders, was made on Lincoln's life which was terminated by Allan Pinkerton. The Confederates also tried to persuade the bordering states who were distant from Washington to succeed, or at least help the Confederate cause. They managed to establish a networkof secret spies and saboteurs in Kentucky and Indiana by 1862. General John Hunt Morgan wished to provoke a full uprising in these states. He raided Ohio and Indiana, but to his dismay they were not successful.


Allan Pinkerton was a famous detective whose exploits were often exaggerated. He actually fell upon his occupation by accident. Pinkerton was on an island cutting barrel wood one day and happened upon a hideout of counterfeiters. He organized a raid and captured the outlaws. As a result he was hired out to do other work of this nature by the Federal government. In 1850 he founded Pinkerton’s National detective Agency in Chicago. Pinkerton first received acknowledgment for his intelligence work during the Civil War when Samuel M. Felton of the Philadelphia, Wilmington & Baltimore Railroad, hired him. His assignment was to catch spies on the secessionist side in Maryland, who plotted to sabotage the railroads. Pinkerton succeeded in doing so He also changed the world beyond what one could ever imagine by stopping a plot to assassinate newly elected President Abraham Lincoln. As a result of his excellent work, he was asked to organize the Secret Service division of the national army in Virginia in 1861. This organization, which he formed, later became the Federal Secret Service.


Thaddeus Sobieski Lowe pursued special studies in chemistry when he was a boy. In 1856 he became interested in ballooning, a field which had already grown through much experimentation in the United States. Lowe’s dream was to eventually cross the Atlantic ocean by Balloon, as preparation he took a flight on his craft, the Enterprise, for nine hours, eventually landing in Unionville, South Carolina. Being a Unionist, and the Civil War starting 8 days prior, he was thrown in jail, but talked his way out of it. In June of 1861 Lowe traveled to Washington to propose the use of balloons by the U.S. Army in the war. Lowe put on an impressive demonstration for Lincoln. On June 18th he ascended above Washington and sent a telegraph report of what he saw via a wire suspended from the balloon, through the War Department’s telegraph system, directly to Lincoln. In doing so Lowe achieved many firsts: first electrical communication from an aircraft to the ground, first such communication to a President of the United States, and first “real-timetransmission of reconnaissance data from an airborne platform. Lincoln was impressed by the capabilities of the balloon. In August 1861, Lowe was hired as a civilian employee of the army. He was employed in a few battles and found success, as well as recognition from Lincoln. Lowe then founded, and became chief aeronaut, of the balloon corps. Upon becoming an employee of the army Lowe built a large reconnaissance balloon, christened the Union. From this balloon he directed artillery fire. As a result of the effectiveness of the balloon he was ordered to make six more like it. The balloon envelopes were made of gored sections of pongee, a type of silk, sewn together in double thickness. The envelope was enclosed in a rope net from which the observer's car was suspended. The envelope was filled with hydrogen gas, which was produced by the action of sulfuric acid on iron fillings in a wagon-borne gas generator. The hot gas produced by the reaction was passed through water cooled copper pipes to lower it’s temperature, and through lime filers for purification. Amazing technologies for the 19th century. The balloons sometimes were tethered to the ground, so they could be reeled back in, or they might be free floating, using only the pilot’s skill for steering. The Balloon Corps participated in many battles with varying success, but they were more often an asset then a nuisance. During a flight of Lowe's a man by the name of Zeppelin observed. He liked what he saw. He brought the idea back to Germany, and invented the Zeppelin, which is similar to the balloons Lowe was using. Zeppelins played a major part in WW II, as well as in the invention of the blimp. Proving once again that without the Civil War one would not be able to watch football games with such ease.


The extensive use of the telegraph and semaphore lines by both sides of the war made cryptography and cryptanalysis a necessity. The lines were often avoided whenever possible for there was a threat that the line might be tapped. On the Union side, Anson Stager devised a word-transpostion cipher, in which the message to be encoded was written as a series of lines across a rectangular grid; the words were selected from the grid according to a pattern of vertical and/or diagonal lines cross the grid, and then reassembled in a scrambled and unintelligible order. Anson’s system was implemented by the U.S. War Department’s Military Telegraph service through out the war, it was a great barrier against the Confederate code breaking efforts. The Confederates were less able cryptographers then the Union. They employed a well known system, which many of our cryptanalysists had a working knowledge of. When ever tappers could intercept transmissions they could decipher it with much success. The growth of the telegraph after the Civil War meant that cryptography was a major concern for the government. It played a big part in many elections and wars prior to the Civil War. Today the NSA is a giant division of the government dealing specifically with cryptology.

Despite the knowledge by both sides that a war was going to take place, neither had made any “pre-war intelligence preparations”. Intelligence was the least of the concerns for both sides, for they felt at the beginning of the war that they had enough understanding of the opposition. They knew each other’s commanders and some individuals even served or went to school together. Each side knew the economic strength, as well as the military holdings, of the other. As can be seen espionage and intelligence gathering were relatively unorganized on both sides of the war. What is important is that many techniques and organizations such as the Secret Service in use today had their roots in the Civil War.

Works Cited

Axelrod, Alan. The War Between the Spies: A history of Espionage during the American Civil War. New York: Atlantic Monthly Press, 1992.

Davis, Kenneth C. Don"t Know Much About The Civil War. New York: Avon Books, 1996.

Deacon, Richard . 'Pinkerton, Allan.' Spyclopedia. 1987.

O"Toole, G. J. A. . 'Civil War.' The Encyclopedia of American Intelligence and Espionage. 1988.

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