The 24th century, defined in the calendar of Earth as being from 2301 until 2400, was a period of great conflict between the various races and organizations of the Milky Way Galaxy. The Federation made contact with several powerful new races such as the Borg, the Dominion and the Cardassian Union, all of whom attacked the Federation on several occasions. The Romulan Star Empire entered a fifty year isolation, from which they emerged far stronger than before. The Borg attempted to assimilate Earth twice, first in 2366 and again in 2373. The latter year also saw the beginning of the Dominion War, which ended in 2375, with the major powers of the Alpha and Beta Quadrants joining together to defeat the Dominion.
- 2311: After the Tomed Incident with the Romulan Star Empire, the Federation signs the Treaty of Algeron, promising no research into or use of any cloaking devices.
- 2344: At the Battle of Narendra III, the Federation vessel USS Enterprise-C defends a Klingon colony against Romulan attackers. Being regarded as an honorable act, the incident cements the Federation-Klingon alliance.
- 2364: A subtle attempt by neural parasites to take full control of Starfleet and to prepare for an all-out invasion of the Federation is discovered and thwarted.
- 2367: After making first contact with the Borg in 2365, a Borg cube attacks the Federation but is destroyed in Earth orbit after the Battle of Wolf 359. Later that year, Klingon Chancellor K'mpec is killed and succeeded by Gowron. His position is quickly challenged but eventually affirmed in the brief Klingon Civil War against the Romulan-influenced, but ultimately inferior, House of Duras.
- 2369: The Bajoran Wormhole is discovered, representing a secure link between the Alpha- and Gamma Quadrants.
- 2372: After the Dominion and the Founders were discovered in the Gamma Quadrant in early 2371, the Federation condemns an attack by the Founder-inflitrated Klingon Empire on the Cardassian Union. A few months later, a Founder-Changeling bombs the Antwerp Conference between the Federation and the Romulans, giving rise to an attempted but failed coup d'état against Federation President Jaresh-Inyo. Near the end of that year, the Federation's and Klingon's old dispute over the Archanis sector escalates, leading to the Klingon's withdrawal from the Khitomer Accords.
- 2373: After the Founder-infiltration of the Klingon Empire is discovered and the Cardassian Union joins the Dominion, the Khitomer Accords are re-instated. In the midst of these events another Borg cube attacks the Federation, but is destroyed near Earth at the Battle of Sector 001. Later that year, the Dominion conquers Deep Space 9, igniting the Dominion War against the Federation-Klingon alliance.
- 2374: After loosing Deep Space 9 to the alliance again, the Dominion conquers Betazed. Later that year, the Romulan Star Empire turns the tide of the conflict as it declares war against the Dominion.
- 2375: The Breen Confederacy allies with the Dominion and launches an attack on Starfleet Headquarters on Earth. Shortly after, Gowron is killed and Martok becomes the new Klingon Chancellor. Near the end of that year, with the help of the Cardassian Rebellion, the alliance manages to repel the Dominion forces, finally capturing Cardassia Prime and ending the Dominion War with the Treaty of Bajor.
- 2376: The Cardassian Union begins to form a democratic government led by elected Castellan Gerim Ertal. The Federation begins providing materiel and humanitarian aid to Cardassia.
- 2378: The USS Voyager returns to the Alpha Quadrant, delivering a crippling blow to the Borg Collective by destroying a Transwarp hub and introducing a debilitating pathogen to the Collective.
- 2379: The Romulan Star Empire is taken over by Praetor Shinzon as the head of a Reman coup d'état. After a false peace offer to the Federation, Shinzon is killed in his attempt to wipe out all life on Earth with thalaron radiation. Shinzon's deposition creates disarray within the Empire. Shortly after, the Federation begins talks with the new Romulan government. The Tholian Assembly formally recalls their ambassador from Romulus in response to growing political unrest within the Romulan Empire.
- 2380: The Federation begins providing material and humanitarian aid to the devastated Romulan Star Empire, and attempts to facilitate negotiations for the re-establishment of permanent government. A weakened Romulan State allows the Klingon Empire to instigate several border conflicts as the Empire seeks to expand into systems formerly annexed from them by the Romulans in centuries past.
- 2384: First contact is made with the Regime and the Shayde, two Elyshan factions operating in the Taevon Expanse, by the USS Frontier. Relations with the formerly secluded Elyshan Empire begin to escalate afterseveral skirmishes between Federation and Elyshan starships in the region between the two powers.
- 2385: The Klingon Empire recovers from its losses during the Dominion War. Representatives of several major powers attend the First Quadrant Powers Summit convened aboard Starbase 386 to address escalating tensions with the Elyshans.
- 2386: Federation starships engage Elyshan vessels in unclaimed space over custody of Ambassador Mordred Ocal and other Federation citizens in what would become the Battle of Altorus. Later that year, the Battle of Starbase 386 results in a narrow Federation victory over Elyshan forces attempting to seize control of the Aldani System.
- 2387: Despite a successful defense of Starbase Gatekeeper led by the USS Frontier, Elyshan factional forces cross into Romulan-held territory left undefended in the wake of the Hobus supernova.
- 2388: The Federation continues providing material and humanitarian aid to the devestated Romulan Star Empire, working with remnants of the Romulan Senate and Romulan Imperial State to facilitate re-establishment of a permanent government. Growing concern over the withdrawn Elyshan Empire and the presence of the Yang Zutal prompts Starfleet Command to make several major staffing changes within the Eighth "Horizon" Fleet.
|23rd century||Timeline||25th century|