Star Trek: Everything We NOW Know About The Lost Era

The USS Leondegrance entered service in the later years of the 23rd Century, remaining operational until the 2330s. From 2301 to 2305, Captain Nyota Uhura took the ship on an exploratory mission of the Lesser Magellanic Cloud. On that mission, the ship made first contact with over one hundred new species.

What exactly the Lesser Magellanic Cloud is or constitutes lacks clarity. The Leondegrance's commemorative plaque names it so, though it could be a reference to the Small Magellanic Cloud that sits outside the borders of the Milky Way Galaxy. Though that may cause havoc with the starship, as demonstrated in Where No Man Has Gone Before, Uhura herself travelled outside the Galactic Barrier in By Any Other Name. In short, we shouldn't make any assumptions.

In 2317, the ship was retired from active exploration and became a training ship, aboard which many new Starfleet officers and cadets broke the light-speed barrier for the first time. One such individual was Jean-Luc Picard, who received his entry certificate for the Faster-Than-Light-Club here. This was later seen in his vault in Remembrance. 

The Autobiography of Benjamin Sisko further states that Captain Sisko's maternal grandparents served aboard the ship, further connecting the various generations of Starfleet officers during this Lost Era of history. 

Captain Uhura remained in charge of the ship until her retirement in 2333. There were plans for a Short Trek to depict an elderly Uhura mentoring a young Jean-Luc Picard, but sadly, this never came to be.