(covers information from several alternate timelines)
World War I, also referred to as The Great War, was a conflict fought mainly in Europe on Earth during the early 20th century. In this conflict, the Central Powers, including Germany, fought the Entente, including France and the United States of America.
After Jonathan Archer restored a damaged timeline, scenes from World War I could be seen in the time stream as the timeline realigned itself, which included the Renault FT tank. Also witnessed by Archer was a contemporary scene of American President Woodrow Wilson inspecting his troops. (ENT: "Storm Front, Part II")
In 1930, Edith Keeler asked time traveler James Kirk if he and Spock had served together in the war, which could have served as a possible explanation of why Spock was addressing him as Captain. (TOS: "The City on the Edge of Forever")
|Earth wars prior to the Federation|
|Crusades • American Revolution • American Civil War • World War I • World War II • Brush Wars • Earth Cold War • Eugenics Wars • World War III • Earth-Kzin Wars • Xindi incident • Earth-Romulan War|
Background information Edit
The original script for "The City on the Edge of Forever" featured a World War I veteran; however, this back-story was dropped from the character. Another cut script reference, from "Yesterday's Enterprise", mentioned the assassination of Archduke Ferdinand in Sarajevo, which contributed to the outbreak of World War I.
Spock's figure of six million deaths falls short of the modern estimate of sixteen million casualties of World War I, but may be a reference to the seven million civilian deaths or the number of deaths as a result of "despotism" or be the result of 23rd century historiography.
John Gill wearing a World War I Iron Cross mirrors Adolf Hitler's decoration with this award for his military service during the war.
A page of the Picard family album created for Star Trek Generations featured a portrait of an ancestor of Jean-Luc Picard in a World War I-era uniform. This portrait actually depicted French army Marshal Ferdinand Foch, which itself was a copy of an actual contemporary postcard, disseminated in 1918 on the occasion of his promotion to Marshal of France and elevation to allied supreme commander.  This portrait did not appear in the finished version of the movie, but was later included in the "Picard's Family Album"-special feature included on the 2004 Star Trek Generations DVD release.
Performers Paul Fix, Ian Wolfe and Art Director Franz Bachelin are the only three known Star Trek affiliated cast and staff who had been veterans of the First World War, with Fix and Wolfe having served in the American armed forces, whereas Bachelin had served as a fighter aircraft pilot for the German side.
While occassionally referenced to in some Star Trek productions, moving World War I footage was only seen in the Star Trek: Enterprise season four episode "Storm Front, Part II" and in the opening credits of "In a Mirror, Darkly" and "In a Mirror, Darkly, Part II", depicting the mirror universe. With the exception of the President Wilson scene, none of the other footage was actual World War I footage though, instead all of it taken from the 1927 silent – as in no spoken dialog – war movie Wings. Shot on location near San Antonio, Texas, the ground battle with the Renault tanks, was intended to depict the 1918 Battle of Saint-Mihiel, with the soldiers seen having been actual service men from the 2nd Infantry Division (which had in effect taken part in the battle) and the Texas National Guard, on loan by Army and Guard to serve as extras on the movie, 3,500 in total. A Paramount Pictures production, it was the very first movie to win the "Best Picture" Academy Award.  In 2012, a restored, extended and remastered version of the movie was released on the occasion of the studio's 100th anniversary, and on which Ben Burtt had worked as restoring sound effects editor. 
Various epuipment historically used in World War I, including the French Renault FT tank, the American 75 mm Gun M1916 field gun, and the German Fokker D.VII fighter aircraft, appeared in the mirror universe opening credits. However, it remains unclear if World War I was also fought in the mirror universe or if those weapons were used in an entirely different conflict.