Timothy Zahn has written many books, yet his most powerful, most captivating, and most brilliant book would have to be The Last Command. This is the 3rd book in the Thrawn Trilogy.
An important factor of the Thrawn Trilogy is that the remaining Grand Admiral, Grand Admiral Thrawn, hopes to amass an army from the shattered remnants of the Imperial fleet, and with this army crush the young, vulnerable New Republic. The trilogy takes place five years after ROTJ.
Thrawn is a strategic genius. The Emperor wanted to keep him secret, so he was never discovered. Thrawn is so brilliant that the rebels would have been pulverized in the space battle taking place above the moon of Endor.
The whole trilogy brings you through breath-taking moments, with so much action it's unbelievable. Zahn brings the world of Star Wars back so beautifully that you could see this as a movie.
There are many awesome moments in the book. I don't want to give away too much, but Leia gives birth, and a clone of Luke is produced. It is just as powerful as him, maybe even more. Luke's severed hand from ESB is found, and it's used to reconstruct him with clone pods found and exploited by Thrawn. The cloning pods are from AOTC, having been hidden by the Emperor.
This book is absolutely wonderful. I will say that some characters meet untimely demises. Timothy Zahn reconstructed the whole story with a better, more malevolent villain. Read these books, AND MAY THE FORCE BE WITH YOU!!!