Two, large, 7.5 kilometer dreadnoughts come out of giant portals in the middle of nowhere alias No Man's Land...
They pop up in an asteroid field, stuck right in there... They should've warped in another galaxy, but they missed a number...
Their portal drives got to recharge and it's likely they will get hit by asteroids, which will make them take even more to charge up their portal drives...
King Ferdinand
Queen Mary
I mean, who can attack two operational dreadnoughts?!
(NOTE: They can be easily detected.)