5th Paragraph

Translation

But when he learnt that the Greeks were [in Greek: "are"]* winning while the Persians were fleeing, he got up and tore his robes. For he was [now, as a result of that fiasco] in extreme difficulty: For, having lost his fleet, he could no longer provide food for his large infantry. He therefore ordered his generals to lead the infantry over land towards Asia while he himself fled lamenting.

 *  In Greek: He heard/saw that at that moment something is happening, in his time.
In English we relate to our time and say: was happening.
When we say: He saw that they were winning we look at it from our point of view, from the moment of time we're in right now. That is our good right. And that way it sounds good to us.
The Greeks looked at events differently, and that is their good right. They said:
He saw that they are winning (i.e. his seeing and their winning is taking place at the same time. This is what he saw and thought: Oh my god, the opposition is winning.
When the Greeks said: "He learnt that they were winning", they actually meant what we express by saying:
"He learnt that they had been winning [at some point in the past when something else happened and the tables were turned maybe]