Sorry to hear you're having trouble with the pre-order. I have queried Random House customer service and hope to hear back from them soon. It seems the .epub retailers (BN, BAM, iBooks, Kobo, etc.) linked on the RH product page are having trouble.
The RH rep got back to me this afternoon. The Fifty Year Sword is now available for NOOK:
No reason was given for the delay.
Have you been able to access the book in the meantime? Pre-orders can occasionally be tetchy and you may need to "archive" and then "unarchive" the book to get it to download.