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It is hard to answer since leadership was all important except where the match was totally uneven. Some of the best never had to actually exchange blows. Asian "hordes" probably were more terrifying than combat effective. (Aetius beat Atilla with a third rate army. Persian immortals left the field to numerically inferior Heruli foederati at Dara. The Light Brigade actually so dumbfounded the Russians that they also withdrew.) I don't count US Confederate States cavalry since they were scouting forces not heavies.