Editing Technology during World War I (section)

== Poison gas ==
{{Main|Chemical weapons in World War I}}
[[Image:Australian infantry small box respirators Ypres 1917.jpg|left|thumb|250px|Australian infantry with gas masks, [[Ypres]], 1917.]]
The widespread use of chemical warfare was a distinguishing feature of the conflict. Gases used included chlorine, [[mustard gas]] and [[phosgene]]. Relatively few war casualties were caused by gas,{{sfn|Raudzens|1990}} as effective countermeasures to gas attacks were quickly created, such as [[Gas mask|gas masks]]. The use of [[chemical warfare]] and small-scale [[Aerial bombing of cities|strategic bombing]] (as opposed to [[tactical bombing]]) were both outlawed by the Hague Conventions of 1899 and 1907, and both proved to be of limited effectiveness,{{sfn|Heller|1984}} though they captured the public imagination.<ref>Postwar pulp novels on future "gas wars" included Reginald Glossop's 1932 novel ''Ghastly Dew'' and Neil Bell's 1931 novel ''The Gas War of 1940''.</ref>

At the beginning of the war, Germany had the most advanced chemical industry in the world, accounting for more than 80% of the world's dye and chemical production. Although the use of poison gas had been banned by the [[Hague Conventions (1899 and 1907)|Hague Conventions of 1899 and 1907]], [[Germany]] turned to this industry for what it hoped would be a decisive weapon to break the deadlock of trench warfare. [[Chlorine]] gas was first used on the battlefield in April 1915 at the [[Second Battle of Ypres]] in [[Belgium]]. The unknown gas appeared to be a simple [[smoke screen]], used to hide attacking soldiers, and Allied troops were ordered to the front trenches to repel the expected attack. The gas had a devastating effect, killing many defenders or, when the wind direction changed and blew the gas back, many attackers.

The wind being unreliable, another way had to be found to transmit the gas. It began being delivered in artillery shells.<ref>{{Cite web|last=Fries|first=Amos|date=1919
 |title=Gas in Attack and Gas in Defense|url=https://apps.dtic.mil/dtic/tr/fulltext/u2/a438002.pdf
 |archive-url=https://web.archive.org/web/20191221212510/https://apps.dtic.mil/dtic/tr/fulltext/u2/a438002.pdf
 |url-status=live
 |archive-date=December 21, 2019
 |website=United States Army}}</ref> Later, [[mustard gas]], [[phosgene]] and other gasses were used. Britain and France soon followed suit with their own gas weapons. The first defenses against gas were makeshift, mainly rags soaked in water or [[urine]]. Later, relatively effective [[WWI gas mask|gas mask]]s were developed, and these greatly reduced the effectiveness of gas as a weapon. Although it sometimes resulted in brief tactical advantages and probably caused over 1,000,000 casualties, gas seemed to have had no significant effect on the course of the war.{{citation needed|date=September 2012}}

Chemical weapons were easily attained, and cheap. Gas was especially effective against troops in trenches and bunkers that protected them from other weapons. Most chemical weapons attacked an individual's respiratory system. The concept of choking easily caused fear in soldiers and the resulting terror affected them psychologically. Because there was such a great fear of chemical weapons it was not uncommon that a soldier would panic and misinterpret symptoms of the common cold as being affected by a poisonous gas.