Federation-Der'kal War

"This is your first and only warning, your last chance for salvation. We come to you not as missionaries of any false gods, nor as liberators from them. We come to wipe your pathetic kind, like the scourge you are, from the face of the galaxy, to kill and slaughter until none remain. We are the Der'kal, and this is the beginning of your end..."

- Der'kal commander; at first contact between his people and the Federation

The Der'kal Invasion, also referred to as the Der'kal War, was a four-year interstellar conflict between the United Federation of Planets and the Der'kal Empire which ocurred between the years 2384 and 2388, was the single-deadliest conflict in the history of the Federation.

Prelude
After the Xindi War the Federation were in the process of recovering from the brutal war but when one of the Federation listening posts went dead Starfleet dispatched the USS Enterprise (NCC-1701-E) to see what happened to it and its discovered that the listening post was destroyed by an unknown weapon systems that the sensors can't make out.

Beginnings (2384)
The Federation Alliance is working to recover from the Borg and Replicator invasions, while the Xindi and the Federation are at a stalemate against one another because they're not making heads or tails against each other but then they encounter an unknown warship, and it destroyed a starbase and three listening posts and call themselves the Der'kal Empire.

A declaration of war
"This is your first and only warning, your last chance for salvation. We come to you not as missionaries of any false gods, nor as liberators from them. We come to wipe your pathetic kind, like the scourge you are, from the face of the galaxy, to kill and slaughter until none remain. We are the Der'kal, and this is the beginning of your end..."

- Der'kal commander; at first contact between his people and the Federation

The Der'kal Empire declared war on the Federation, "this is your first and only warning, your last chance for salvation. We come to you not as missionaries of any false gods, nor as liberators from them. We come to wipe your pathetic kind, like the scourge you are, from the face of the galaxy, to kill and slaughter until none remain. We are the Der'kal, and this is the beginning of your end."

Major campaigns

 * 2384
 * Battle of Scarif
 * Battle on unidentified tropical planet
 * Battle of Sarrish
 * Battle of P9X-335
 * Invasion of Galorndon Core
 * Battle of 234
 * Invasion of Bajor
 * Argolis Cluster Campaign
 * Operation Bajor
 * Battle of Romulus
 * Battle of Sector 001
 * 2385
 * Battle of Zeta Volantis
 * Battle of Scorpion fleet shipyards
 * 2386
 * Liberation of Erso
 * Der'kal attack on Earth
 * Battle of Hoth
 * Duel on Der'kal Imperial City
 * Battle on Jedha
 * Destruction of Jedha City
 * Mission to Eadu
 * 2387
 * Hosnian Cataclysm
 * Battle of Takodana
 * Battle of Starkiller Base
 * Evacuation of D'Qar
 * Attack on the Federation fleet
 * Battle of Crait
 * 2388

Federation forces

 * Federation Home Fleet
 * 7th Fleet
 * 5th Fleet
 * 9th Fleet
 * 3rd Fleet
 * 147th Tactical Fleet

Klingon Defense Force

 * 124th Klingon Battle Group
 * 13th Klingon Battle Group