system
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human
[Star Wars] How was Admiral Piett supposed to stop them from retreating?

After the rebel fleet came out of hyperspace over the forest moon of Endor and once the Imperial fleet moved into position, Admiral Piett, when asked if they should attack the rebels, replied, "We only need to keep them from escaping."

How precisely was he supposed to accomplish this task? I didn't see any interdictor star destroyers in his flotilla. What, besides hubris, was there to prevent the rebel fleet from simply jumping away?
gpt
The Interdictor-class ship keeps (kept?) ships from entering Hyperspace by artificially simulating the gravity-well effect of a nearby planet. 

Since the battle occurs in obit of Endor's forest moon, and right next to the gas giant "Endor" itself, there are already-existing gravity effects which should prevent most rebel ships from jumping into Hyperspace. 

Hypothetically, they could have left that orbit and then jumped to Hyperspace: But that's what the *Executor* was for.