>>24527558 (OP)>Was Duke Leto just fucking stupid?Arrakis gets rotated between Houses constantly, so that no one house can get too comfortable there and monopolize the Spice. It being transferred is not a big deal in itself, it's not Arrakis being given over to Atreides that makes Harkonnens hate them, they were mortal enemies for generations prior to that (tho we don't know why exactly beyond "Harkonnens are angry tards"). It's a big deal in this particular case because - as the book spells out verbatim - transfer of holdings is moment of greatest vulnerability for any House, and Leto knows that his conflict with Harkonnens and the Emperor is at it's peak, so they are blatantly using the transfer as an opportunity to make Atreides vulnerable for a moment and harm them.
Leto literally spells out that he knows it's a trap and explains this to his advisors. His mistake was in expecting Harkonnens and the Emperor to try and undermine him with kanly and sabotage, so that either he and his line die to assassins or he fails to fulfill the spice quotas, which damages the CHOAM profits, which makes every House in Landsraad really pissed at Leto, destroying him as a parliamentary threat to Corrinos. His plan was getting ready for kanly with his household guard and achieving record Spice yields through collaborating with the Fremen, which would massively boost CHOAM profits and finally make Leto way more popular than Shaddam, at which point his House would seize the throne bloodlessly through earnest support of most of the other Houses, the Emperor's attempt to humiliate Atreides backfiring and ending up elevating them instead. He was playing the long quiet game where he wins by being more competent and agreeable than Shaddam, without ever entering a direct confrontation.
His failure was in not realizing that the Emperor knows he can't win the long game, and is therefore desperate enough to secretly give the Harkonnen his Sardaukars and just greenlight an open Harkonnen attack.
He cannot refuse the Arrakis because refusing a direct (and more importantly, traditional) order of the Emperor would escalate the conflict to an open confrontation and then even with his popularity in the Landsraad most Houses would prefer to sit out an open war against the throne seemingly started for the Atreides' right to not do the job all houses are reasonably expected to do (run Arrakis for a while). So he'd be left alone against both Harkonnens and Corrino, and gotten curbstomped just as he did in the actual plot, only Shaddam doesn't even need to hide his involvement, he'd be rightfully putting down a rebellious vassal.
