According to history, Pompey's army had a critical weakness in that it had a large number of foreign mercenaries in it. These soldiers did not speak good Latin, and could not coordinate smoothly with the rest of the army in the heat of battle.
The use of making a raft out of floating corpses is nearly identical to the Black Freighter storyline in The Watchmen (2009) film. In both, bloated corpses from a sunken ship are tied together to form a raft and it is used to escape a deserted island. In both stories they also catch a live seagull and eat it raw and later vomit it up.