(Book 1 spoilers)

A bit of an unusual question. But what happened to Caladan after the Harkonnen took Arrakis. Did they conquer Caladan as well? I must admit, I haven't read all the books so I may have missed some of the info.

The Atreides all left Caladan, when they went to Arrakis. Nothing is said in the books about what happened to Caladan during the story of Dune.

Story spoilers since I don't know how far you have gotten. (spoilers from the end of Dune and the next two: Messiah and Children)

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After Shaddam's defeat Jessica went back to Caladan with Gurney Halleck. And they lived there along with Atreides guards, for some time.

Heretics and Chapterhouse spoilers: the planet in this time was renamed to Dan and Darwi Odrade comes from this planet.

[ 01-16-2005, 08:27 AM: Message edited by: dplax ]

To add to Dplax's informative reply:
In the Dune social paradigm, the emperor gave planets (and the populations thereof) over to individual aristocratic Houses for them to manage and rule over, much like a development company may be given an exclusive business contract in a particular region by a national government nowadays.
At the beginning of Dune, House Atreides has been ordered to relinquish their jurisdiction of Caladan, and have instead been given the charge of Arrakis. The common population of Caladan remained behind and simply had to accept the next royal House that was given rulership over them.
A slight anomaly exists in this system whereby House Harkonnen maintain their control of Geidi Prime while simultaneously ruling Arrakis after their violent coup against Duke Leto. Anyone know what's up with that? I suppose some Houses are granted multiple charges, if they are large and successful enough to maintain them. Keeping in mind that the Atreides charge of Arrakis was a trap devised by the Emperor to destroy the popular Duke Leto right from the outset. So perhaps the Emperor wanted to get all of the Atreides in one place at one time so he could underhandedly eradicate them all in one fell swoop under the guise of the Atreides-Harkonnen feud...

[ 01-16-2005, 09:50 PM: Message edited by: The Hierophant ]