Order 65 was an order meaning all military personnel should drop what they were doing at once, PWN the Supreme Chancellor and give immediate Powah to the Galactic Senate. Palpatine issued this order once by mistake, the results were almost irreversible, Palpy had to kill all 900 Gazillion Clone troopers and got Pwnd by Fordo (who Pwnd big-time). He had to transfer his spirit to a clone-body and start all over again with a new blockade on Nabooboo, initiating yet another Clone War and so on and so on. Many years later he finally did it all right and ordered Commander Cody to execute order 66.