Possibly the winter battle in Finland, ww2, Nazi troops layer down arms after 1 day
After the PQ-17 convoy disaster during WW2, an officer involved in operation "Pedestal" en route to Malta said "I don't care what signals i get from whom, so long as there's a merchant afloat I'm putting my ship alongside her and we're going to Malta". He was willing to disobey orders on the moral basis of not abandoning a friendly ship. Might not be the "biggest example" but one that comes to my mind.
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