Caesar's opinion of the Nervii was that they had shown great fighting spirit in carrying an attack forward so vigorously on to difficult ground and in continuing to fight stubbornly when the tide of battle turned irretrievably against them. Caesar talks of a grimly inspiring image of the last of the Nervii who were atop a mound of corpses of their own warriors and shouting in defiance towards the Romans, fighting till their last breath. He goes on to say that they had outstanding courage, for they launched a surprise attack, crossed a river up its banks, then rushed on to attack all with a fighting spirit. He glorifies his victory by stating how well his army did without having to be ordered to launch a counter-attack. It is probable that his soldiers were experienced veterans who were able to hold off their onslaught. He evidently mitigates his losses by not mentioning the Roman casualties, or conceding that they were in serious danger of defeat, as appears to have been the case. While Caesar appears to give a relatively frank account of the course of the battle, in "The Conquest of Gaul", this remains one of the only primary sources. And since it was written by Caesar, much is unknown of the Nervii's perspective, such as the extent to which Boduognatus planned the attack and directed his forces during the battle.