2256 — stexpanded

Events

The USS Potemkin is the only Constitution-class Flight I vessel not upgraded to the Flight II configuration, but to the Bonhomme Richard-subclass standard. (Star Fleet Starship Recognition Manual: Report: Constitution Heavy Cruisers)
The Roman Catholic Church appoints Kej'ric of the House of Kej'tar Bishop of Qo'noS. (The Starfleet Museum: Avenger- and Predator-Class Destroyers)
Two Crossfield-class science vessels, the USS Discovery and the USS Glenn, are assigned to test an experimental displacement-activated spore hub drive. (DIS: "Context is for Kings")

28 March:
- The Soyuz-class tactical frigate USS Accord is first commissioned. (Star Trek: Accord: "The USS Accord Fictional Timeline, v. 1.32")
- Lieutenant Commander Melissa Sturdevant transfers to the newly commissioned USS Accord to become its second officer. She meets Lieutenant Commander Nikolai Barstow for the first time; though seven years her junior, he is the ship's first officer. (Star Trek: Accord: "Year One"; Star Trek: Shadowstar Station)

11 May:
- The Federation-Klingon War begins with the Battle of the Binary Stars. (DIS: "The Vulcan Hello", "Battle at the Binary Stars", "Context is for Kings")

While en route to Starbase 36, the medical frigate USS Hiawatha -- believed to have been destroyed by Klingon forces during the Federation-Klingon War -- had instead crashed on the surface of an interstellar asteroid. It was discovered more than ten months later by the USS Discovery. (DIS: "Brother", "Far From Home")

Phillippa Georgiou dies aboard the Klingon Sarcophagus ship. (DIS: "Battle at the Binary Stars")

Commander Ellen Landry, chief of security of the Discovery, is killed by a tardigrade. ("The Butcher's Knife Cares Not for the Lamb's Cry")
The Crossfield-class science vessel USS Glenn is destroyed with all hands when it runs into a Hawking radiation firewall. ("The Butcher's Knife Cares Not for the Lamb's Cry")

Cadet First Class Sylvia Tilly is assigned to the USS Discovery for her senior-year field assignment. ("A New Assignment", derived from DIS: "Context is for Kings")