Im going on a six month vacation what do I write in a memo to my employees about what they need to do and expectations while Im gone?

Im going on a six month vacation what do I write in a memo to my employees about what they need to do and expectations while Im gone?
Tell them they need to keep up productivity while you are gone, you expect them to work as hard as if you were there. Remind them you will know if they were slack in their work while you were gone. Offer a bonus for those who were the most productive by the time you return.