Here is one of the most legendary battles in Federation history: the Aridaginatan War. Most significantly, the 2398 Battle Of Deep Space 9.
This battle would be the catalyst in which the Aridaginatans then time travel to the 21st century in an attempt to kill Sunset Shimmer and the Rainbooms. The Sunset Shimmer then pursued them around the sun there. However, the Aridaginatan Queen’s murder plans were thwarted by Captain Becky Ray Shoichet and the crew of the USS Sunset Shimmer, along with help from the Rainbooms and Q himself, who was finally revealed to be Discord all along.