Echoes of Krypton is the first chapter of The Last Son, Book One: Gatherings.
Following the trial and banishment of General Zod to the Phantom Zone, scientist Jor-El finds that the planet Krypton is about to explode and is unable to convince the populace of his theory. He and his wife sen their infant son to Earth. There, he is found and raised by Jonathan and Martha Kent.
Years ago, on the planet of Krypton, its inhabitants went to war against the Shi'ar Empire that entered their galaxy and invaded their planet. Within 6 years, the Kryptonians repelled the Shi'ar through their powerful technology and thanks to the efforts of General Dru-Zod, the head of the Kryptonian Defense Force, who broke the siege aided by the new weaponry developed by Krypton's most brilliant scientist, Jor-El, Zod's longtime friend. With the Shi'ar defeated, the Shi'ar Emperor, Kral'Nor, was overthrown and exiled by a group of Shi'ar that opposed the war and the expansion, led by another of the Imperial Family. The New Shi'ar Empire quickly negotiated for peace, ending the war.