Alien Armies at the Gate, My Sword Points to the Stars

After Earth fell in a brutal intergalactic war, his entire nation sacrificed everything to send him back in time. Reborn before the apocalypse, he takes command of a secret national initiative. This time, he won't fight alone—he links an immortality trait to his entire homeland: as long as he lives, his people cannot fall. When alien legions invade, they expect easy prey. But can an immortal nation rewrite the rules of war and become the universe's ultimate nightmare?