The Dark Tide Duology was written by Michael A. Stackpole and contained the novels The New Jedi Order: Dark Tide I: Onslaught and The New Jedi Order: Dark Tide II: Ruin. The duology is part of the New Jedi Order series.
It was originally going to be a trilogy, but The New Jedi Order: Dark Tide: Siege was removed.
In June of 2000 both novels in the duology were published in single volume Hardcover exclusively by the Science Fiction Book Club.
ISBN 0-7394-1111-X Science Fiction Book Club Edition, June 2000