LeftHandofGod
"And perhaps it's time to remind you why Younger Powers are capable of throwing you over." Commodore Soren muttered. He, using his connection to the ship, transmitted orders to everyone in the small fleet, heavily encrypted beyond Imperial power to decrypt.
(these fleet-wide transmissions are for me only, you don't hear this)
"Commodore Soren to Patrol Group One Thirty, stagger-fire gravitocannons, point nine c, execute command upon receipt."
At that moment, multiple ten-ton slugs are fired off the gravitocannons of the vessel at ninety per-cent the speed of light, multiple gigatons of destructive force is enacted upon the Imperial vessels while the gravitocannons fire individually to keep Imperial voidshields down.
"Patrol Group One Thirty, launch thermofission torch-missiles, target all Imperial vessels, execute upon receipt."
At that moment, thermonuclear missiles on large scales begin launching at the Imperial vessels using microfusion torch drives, accelerating them beyond normal 0.1 c with a payload of, again, multiple gigatons, and then something unexpected happened. While the Imperial vessels had never fought a lot of people with this technology, they are there... Multiple massive space-time distortions are detected from the Sovereignty vessels, along with space-time bubbles that shield them and prepare them for the next wave, only opening holes for gravitocannon fire.
The_Overseer
The Kyrian vessels witness their first ever shot of a gravitocannon - many gigatons of sheer destructive power being directed at the Imperium vessels, followed by arrays of thermonuclear missiles of at least ten gigatons of destructive power - it seems they have refined their nuclear warheads over the centuries.
{--TRANSMISSION--}
"They attacked first because they didn't like the idea of us saving a group of primitives that could be something great once - just look at their cruiser crashing towards the planet at full burn!"