The Battle of Caleb IV (STO)
From Trekipedia
Stardate Unknown: Rogue temporal operatives strike during one of the Federation's greatest defeats. Stop them before a bad situation becomes terminally worse!
We have a situation in the Caleb system. The Klingons are massing a battle fleet in that sector, and it's pointed at Federation space.
I'm leading a force to respond to this aggression, and I want you to be a part of it. If they cross the line, we need to be ready for anything.