World War I

World War I


World War I, which spanned a four-year period between 1914 and 1918, erupted as a result of the complicated European alliance system. The assassination of Austrian Archduke Ferdinand, and his wife, Sophie, by Serbian nationalists sparked pan-European conflict when Russia, backed by France, declared their intent to defend Serbia, should Austria declare war. The Austrian government, with its ally Germany, declared war on Serbia three days later. British forces joined the French and Russians, but the United States, home to large immigrant populations of all of the fighting nations, resolved to remain out of the conflict.

The United States declared its neutrality, but the nation harbored Allied sympathies. United States manufacture and trafficking of munitions and supplies to aid British and French forces angered Germany and Austria. The German Navy attacked American ships, potentially loaded with contraband, in the Atlantic, and sent intelligence agents to conduct sabotage operations within the United States. In 1917, German hostility prompted the United States to enter the conflict in Europe.

The war ended in 1918, followed by the formal surrender of German and Austrian forces with the signing of the Treaty of Versailles. However, World War I forever changed modern warfare, introducing the concepts of total warfare and weapons of mass destruction.

National intelligence communities. At the outbreak of the war, many nations had weak or fledgling national intelligence communities. The French government and military both maintained trained intelligence forces, but no central agency processed intelligence information, or facilitated the distribution of critical intelligence information. Russia had special agents of the Czar, and secret police forces, but its foreign intelligence infrastructure was almost non-existent.

Members of the first contingent of New Yorkers drafted into the United States Army are shown lined up in front of their barracks at Camp Upton, Long Island, New York, as America enters World War I in 1917. AP/WIDE WORLD PHOTOS.
Members of the first contingent of New Yorkers drafted into the United States Army are shown lined up in front of their barracks at Camp Upton, Long Island, New York, as America enters World War I in 1917.

The United States developed stronger domestic intelligence and investigative services in the decade before World War I. However, the country's lingering isolationism and neutral posture in the war hampered the development of a foreign intelligence corps until the United States entered the war in 1917.

Britain had a well-developed military intelligence system, coordinated through the Office of Military Intelligence. British intelligence forces engaged in a range of specialized intelligence activities, from wiretapping to human espionage. The vast expanse of British colonial holdings across the globe provided numerous outposts for intelligence operations, and facilitated espionage. British forces were among the first to employ a unit of agents devoted to the practice of industrial espionage, conducting wartime surveillance of German weapons manufacturing.

Of all the warring nations in 1914, Germany possessed the most developed, sophisticated, and extensive intelligence community. The civilian German intelligence service, the Abwehr , employed a comprehensive network of spies and informants across Europe, North Africa, the Middle East, and in the United States. German intelligence successfully employed wire taps, infiltrating many foreign government offices before the outbreak of the war.

World War I forced most national intelligence services to rapidly modernize, revising espionage and intelligence tradecraft to fit changing battlefield tactics and technological advances. The experience of the war formed the first modern intelligence services, serving as forbearers of the intelligence communities in France, Britain, Germany, and the Untied States today.

Sabotage. German intelligence trained special agents, most of whom used professional or diplomatic covers in the United States, to conduct acts of sabotage against United States industries that aided the British, French, and Russian allied forces in the war. International rules of engagement limited the ways in which Germany and Austria-Hungary could provoke or attack the declaredly neutral United States. German high command desired to cripple United States aid capabilities, but not provoke the nation to enter the conflict. German undercover agents attacked railroads, warehouses, shipyards, and military instillations in 1914 and 1915. Agents attempted to make these attacks appear as accidents, but United States authorities caught several potential saboteurs before they destroyed property, unmasking the German plot. Anti-spy hysteria fueled public fear and anger regarding the acts of German saboteurs.

German and Austrian agents carried out more than 50 acts of sabotage against United States targets on American soil during the course of the war. Most of the attacks occurred in New York City and the region surrounding New York harbor. The most famous and devastating attack, the sabotage of Black Tom Pier, shook buildings and broke windows across New York City and suburban New Jersey. The July 29, 1916, explosion destroyed several ships and waterfront ammunition storage facilities. The attack decimated Black Tom Pier, the staging area for most shipments bound for the Western Front in Europe.

German sabotage attacks in the United States, while successful, only managed to strike at a handful of military and shipping targets. The United States government continued to aid British and French forces in Europe, but the attacks inflamed pro-war sentiment.

Communications and cryptology. Advancements in communications and transportation necessitated the development of new means of protecting messages from falling into enemy hands. Though an ancient art, cryptology evolved to fit modern communication needs during World War I. The telegraph aided long-distance communication between command and the battlefront, but lines were vulnerable to enemy tapping. All parties in the conflict relied heavily on codes to protect sensitive information. Cryptology, the science of codes, advanced considerably during the first year of the war. Complex mathematical codes took the place of any older, simple replacement and substitution codes. Breaking the new codes required the employment of cryptology experts trained in mathematics, logic, or modern languages. As the operation of codes became more involved, the necessity for centralized cryptanalysis bureaus became evident. These bureaus employed code breakers, translators, counterintelligence personnel, and agents of espionage.

The most common codes used during the war continued to be substitution codes. However, most important messages were encrypted. Encryption further disguised messages by applying a second, mathematical code to the encoded message. Encryption and coding both required the use of codebooks to send and receive messages. These books proved to be a security liability for the military. During the course of the war, four separate German diplomatic and military corps code books fell into the hands of British intelligence, compromising the security of German communications for the rest of the war.

Both the Germans and the British broke each other's World War I codes with varying success. The German Abwehr broke several British diplomatic and Naval codes, permitting German U-boats to track and sink ships containing munitions. British cryptanalysis forces at Room 40, the military intelligence code-breaking bureau, successfully deciphered numerous German codes, thanks in large part to the capture of German codebooks. In 1917, British intelligence intercepted a diplomatic message between Berlin and Mexico City, relayed through Washington. The message, known as the Zimmerman Telegram, noted German plans to conduct unrestricted warfare against American ships in the Atlantic, and offered to return parts of Texas and California to Mexico in exchange for their assistance. Discovery of the Zimmerman Telegram prompted the United States to enter World War I.

Cryptology, once the exclusive tool of diplomats and military leaders, became the responsibility of the modern intelligence community. After World War I, many nations dissolved their wartime intelligence services, but kept their cryptanalysis bureaus, a nod to the growing importance of communications intelligence and espionage.

Trench warfare and the evolution of strategic espionage tradecraft. The advent of trench warfare necessitated the development of new surveillance and espionage techniques to locate enemy positions and gauge troop strength. Crossing "no man's land," the area between trench fronts, was dangerous, and using human scouts proved costly to both sides in the early months of the war. Military intelligence officers instead relied on networks of local citizens for information on enemy advances and supply lines. Finding sympathetic locals was possible for both sides in the trenches of Northern France, as the battlefront crossed the linguistically and culturally diverse German-French region of Alsace-Lorraine.

The airplane was a new invention when war broke out in Europe. Though the device was unproven in war, German commanders recognized that air combat and aerial bombardment were the most significant war tactics of the future. Britain developed fighter squadrons of its own to combat the German air menace. Despite the fame of the German Red Baron and World War I aerial dogfights, airpower was a very small part of the war effort on both sides. However, low-flying airplanes proved invaluable surveillance and intelligence tools, permitting military command to obtain accurate and up-to-date information on enemy trench locations and fortifications. British forces experimented with aerial surveillance photography, trying several cameras, but the medium had little success during the course of World War I.

German and Austrian forces introduced the use of balloons to monitor weather patterns and deliver explosive charges. Sometimes, dummy balloons were sent across enemy lines so that scouts could monitor where individual balloons were shot down, thus mapping probable enemy strongholds. British and French forces soon reciprocated by using balloons of their own, but by the time they introduced the devices, balloons signaled the impending use of a far more sinister weapon, poison gas.

Chemical weapons. Although military strategists during the nineteenth century noted the potential use of poison gas on the battlefield, the development of the first, World War I–era chemical weapon happened by accident. Seeking to conserve TNT, British and German forces substituted two different agents, Lyddite and Dianisdine salts respectively, into their explosive charges. The chemicals produced a tearing agent and mild respiratory irritant, sending victims into violent fits of sneezing.

The French first developed strong tear gas agents for battlefield use in June 1914. French forces first employed the gas in the form of tear-gas grenades, in August 1914. German scientists created a similar agent, and were the first to research various types of poison gas for extensive battle use. In October 1914, the Germans fired the first gasfilled shells. A few months later, experiments with filled shells were unsuccessful. Gasses failed to properly vaporize on the Eastern Front during the freezing winter. Variable winds on the Western Front made dispersal of gasses difficult.

By 1915, the German, French, and British armies all sought to develop chemical agents that would help end the relentless stalemate of trench warfare. Outdated battlefield tactics ordered soldiers to charge fortified trenches, across open fields strewn with barbed wire. Military commanders hoped poison gas would help soften or destroy manned defenses, permitting successful seizure of enemy positions.

The first major use of strong poison gas was an asphyxiant and respiratory irritant, chlorine, at the Second Battle of Ypres. German forces mounted a heavy bombardment of the French, British, and Algerian Ypres Salient. In the evening, the firing grew more intense, and Algerian troops noticed a peculiar yellow cloud drifting toward the Salient. French military commanders believed the yellow smoke hid an oncoming German advance, so soldiers were ordered to stand their ground and man machine gun defenses. As a result, many men died and the Salient was broken, forcing the Allies to retreat.

Germany drew immediate criticism for its inhumane use of gas on the battlefield. German diplomats assured rival powers that poison gas would be used regularly against their forces, provoking further condemnation. Both sides of the conflict employed agents of espionage to spy on the production of new weapons. Informants told Allied authorities about the possible German use of chlorine gas at Ypres. After Ypres, intelligence personnel changed its tactics to obtain specific information on the gasses each side was producing, and how they intended to weaponize the chemicals.

The British government commissioned Special Gas Companies to create poisons for wartime uses. On September 24, 1915, Allied forces retaliated the initial German gas attacks. Setting some 400 chlorine gas canisters along the German lines at Loos, British forces began the gas attack at dawn. A few minutes after sunrise, the prevailing winds suddenly shifted, driving the cloud of gas back over British lines. The operation was disastrous, Britain suffered more causalities on the day than did Germany.

After the incident at Loos and several similar gas reversals, both British and German forces experimented with different means of delivering poison gasses to minimize friendly-fire exposure to the chemicals. The creation of stronger, more deadly agents, such as Phosgene (an asphyxiant) and later Mustard Gas (a blister agent that burned exposed skin and eyes), necessitated a remote delivery system. Gas canisters were dropped from balloons and airplanes, but the system was not always reliable and targeting specific locations was difficult. Advancement in ammunition design, and the chemical agents themselves, finally permitted chemical agents to be placed in the payload of long-range artillery shells.

Despite more efficient delivery mechanisms, chemical warfare eventually became less effective on the battle-field. All armies in the conflict quickly devised protective gear to shield soldiers from exposure to chemical agents. Cotton wraps dipped in baking soda and gas masks greatly reduced the number of casualties from most gasses, though they offered no protection from the increasingly used Mustard Gas. Battlefield toxins became more deadly, especially with the limited use of cyanide derivatives and prussic acid, a crippling nerve gas. However, protective clothing and gas masks limited mortality from rare gasses.

Better intelligence also helped combat casualties incurred from gas attacks. Intelligence aided troops in the trenches to reposition to avoid an impending attack. Identification of the type of gasses possessed by the immediate enemy corps further detracted from the element of surprise, upon which gas attacks heavily relied. Despite its diminished success, gas continued to be regularly deployed.

The legacy of World War I. By the end of World War I, over 100,000 people were killed, and one million injured, by poison gas attacks. Those injured often suffered debilitating injuries, creating further public ire for chemical weapons. Civilians were inadvertently injured by contaminated areas, especially by the long-lingering mustard gas. After the war, the newly established League of Nations moved to amend the international rules of engagement to disallow the use of poison gas. Though the motion gained public and diplomatic support, military leaders were hesitant to agree to a total ban on chemical warfare. In 1925, the Geneva Protocol outlawed the use of chemical and biological weapons in war against human targets. However, the treaty did not prevent their further use, and chemical and biological weapons attacks by rogue nations or terrorist organizations have now reemerged as a global threat.

The Armistice created the political map of Europe that sparked the powder keg of World War II. The German government collapsed under the weight of reparation payments and hyperinflation, only to emerge from economic troubles under the reign of Adolf Hitler and his Nazi Party. In the East, small ethnic nations were combined into larger states, embittering nationalists that hoped the war would bring freedom from Austrian, Russian, or German domination. Russia began a tumultuous revolution in 1917, withdrawing from the war to concentrate on domestic affairs.

The legacy of World War I extends beyond World War II, however. Many nations participating in the conflict realized the necessity for some sort of permanent intelligence services, whether cryptology and surveillance units, or large government intelligence agencies. The nature of war, and the business of intelligence in wartime and peacetime were altered by the events of World War I.



Gilbert, Martin. The First World War: A Complete History. New York: Henry Holt, 1996.

Keegan, John. The First World War. New York: Vintage Books, 2000.


Black Tom Explosion
Room 40
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