Complex sentence: When Hughes found out about the rival film, he did everything he could to sabotage "The Dawn Patrol" by harassing Hawks and other studio personal, hiring a spy that was quickly caught and finally suing First National for copyright infringement.
Split into simpler sentences: When Hughes found out about the rival film, he did everything he could to sabotage "The Dawn Patrol". He harassed Hawks and other studio personal, hired a spy that was quickly caught and finally sued First National for copyright infringement.