Chemical weapons in World War I in the context of "Deterrence theory"

World War I, or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a global conflict between two coalitions: the Allies (or Entente) and the Central Powers. Major areas of conflict included Europe and the Middle East, as well as parts of Africa and the Asia-Pacific. The war saw important developments in weaponry including tanks, aircraft, artillery, machine guns, and chemical weapons. One of the deadliest conflicts in history, it resulted in an estimated 30 million military casualties, and 8 million civilian deaths from war-related causes and genocide. The movement of large numbers of people was a major factor in the deadly Spanish flu pandemic.

The causes of World War I included the rise of the German Empire and decline of the Ottoman Empire, which disturbed the long-standing balance of power in Europe, the exacerbation of imperial rivalries, and an arms race between the great powers. Growing tensions in the Balkans reached a breaking point on 28 June 1914 when Gavrilo Princip, a Bosnian Serb, assassinated Franz Ferdinand, the heir to the Austro-Hungarian throne. Austria-Hungary blamed Serbia, and declared war on 28 July. After Russia mobilised in Serbia's defence, Germany declared war on Russia and France, who had an alliance. The United Kingdom entered the war after Germany invaded Belgium, and the Ottoman Empire joined the Central Powers in November. Germany's strategy in 1914 was to quickly defeat France before transferring its forces to the east, but its advance was halted in September, and by the end of the year the Western Front consisted of a near-continuous line of trenches from the English Channel to Switzerland. The Eastern Front was more dynamic, but neither side gained a decisive advantage, despite costly offensives. Italy, Bulgaria, Romania, Greece and others entered the war from 1915 onward.

James Bryant Conant (March 26, 1893 – February 11, 1978) was an American chemist, a President of Harvard University, and the first U.S. Ambassador to West Germany.

During World War I, he served in the U.S. Army, where he worked on the development of poison gases, especially lewisite. He became an assistant professor of chemistry at Harvard University in 1919 and the Sheldon Emery Professor of Organic Chemistry in 1929. He researched the physical structures of natural products, particularly chlorophyll, and he was one of the first to explore the sometimes complex relationship between chemical equilibrium and the reaction rate of chemical processes. He studied the biochemistry of oxyhemoglobin providing insight into the disease methemoglobinemia, helped to explain the structure of chlorophyll, and contributed important insights that underlie modern theories of acid-base chemistry.

A weapon of mass destruction (WMD) is a biological, chemical, radiological, nuclear, or any other weapon that can kill or significantly harm many people or cause great damage to artificial structures (e.g., buildings), natural structures (e.g., mountains), or the biosphere. The scope and usage of the term has evolved and been disputed, often signifying more politically than technically. Originally coined in reference to aerial bombing with chemical explosives during World War II, it has later come to refer to large-scale weaponry of warfare-related technologies, such as biological, chemical, radiological, or nuclear warfare.

The histories of biological and chemical warfare date from antiquity to the modern period, with toxic gases used on a vast scale in World War I. In the 20th century, nuclear weapons were first developed, and were used in war twice, in the atomic bombings of Hiroshima and Nagasaki. Biotechnology allowed for the enhancement of pathogens as weapons, and advanced chemical weapons such as nerve agents were developed. Radiological weapons have never been used or mass-produced.

In military usage, a barrage is massed sustained artillery fire (shelling) aimed at a series of points along a line. In addition to attacking any enemy in the kill zone, a barrage intends to suppress enemy movements and deny access across that line of barrage. The impact points along the line may be 20 to 30 yards apart, with the total line length of the barrage zone anything from a few hundred to several thousand yards long. Barrages can consist of multiple such lines, usually about 100 yards apart, with the barrage shifting from one line to the next over time, or several lines may be targeted simultaneously.

A barrage may involve a few or many artillery batteries, or even (rarely) a single gun. Typically each gun in a barrage, using indirect fire, will fire continuously at a steady rate at its assigned point for an assigned time before moving onto the next target, following the barrage's detailed timetable. Barrages typically use high-explosive shells, but may also be shrapnel, smoke, illumination, poison gas (in World War I), or potentially other chemical agents. Barrages are in contrast with concentrated artillery fire, which has a single specific target such as a known enemy position or structure, and in contrast with direct fire which targets enemies within the direct line of sight of the gun.

Phosgene is an organic chemical compound with the formula COCl₂. It is a toxic, colorless gas; in low concentrations, its musty odor resembles that of freshly cut hay or grass. It can be thought of chemically as the double acyl chloride analog of carbonic acid, or structurally as formaldehyde with the hydrogen atoms replaced by chlorine atoms. In 2013, about 75–80 % of global phosgene was consumed for isocyanates, 18% for polycarbonates and about 5% for other fine chemicals.

Phosgene is extremely poisonous and was used as a chemical weapon during World War I, where it was responsible for 85,000 deaths. It is a highly potent pulmonary irritant and quickly filled enemy trenches due to it being a heavy gas.