Kendal Ozzel is a human Imperial fleet admiral from Carida, played by Michael Sheard in The Empire Strikes Back (1980). He commands Death Squadron from the bridge of the Executor for approximately eleven minutes of screen time.
The mistake
Ozzel dismisses the probe droid's report from Hoth as another false lead, is overruled, and then brings the fleet out of lightspeed close enough to the planet that the Rebels have time to raise their shield. Darth Vader opens a channel to the bridge and strangles him mid-sentence, promoting Captain Piett to admiral in the same breath.
Why the scene works
It is the most economical piece of character establishment in the trilogy. Two films of Imperial hierarchy — the ranks, the deference, the enormous machine of it — are shown to be worth nothing at all against one man's irritation. Everything Piett does for the rest of the film is coloured by having watched it happen from two metres away.
The accidental service to the Rebellion
Later material draws out the irony without labouring it: Ozzel's blunder is what gives the Alliance time to evacuate Echo Base. The transports that get out of Hoth because of his error are a meaningful part of what is still fighting at Endor a year later. The Empire's worst admiral did more for the Rebellion than most of its pilots.
