Exile's End

From the introduction:

No one is sure exactly what date it occurred, but as the second millennium after the destruction of Earth was coming to an end an event occurred that to this day is not fully understood. There are unconfirmed accounts that the Destroyers had something to do with it, some say it was another alien race that interfered. Some say it was God. Suddenly, and unequivocally, all the Jump Gates simultaneously emitted a burst of Fidich Radiation so strong that nearby space stations were wiped clean of all living organisms, any starships in the vicinity became giant microwave ovens and cooked their crews. Then they shut down.