If it was a civilian who did this, well, we have to be careful about how to define this person because civilians never formally swear loyalty to the nation, at least not in ancient times. So if civilians do this, we usually cut them some slack. But Wu was a general, which means he swore that he would defend his country against its enemy at all cost. Many have indeed paid the price and died while defending their country. Why in the world should Wu be excused for surrendering to his enemy for fear of death? A soldier is prepared to die for his country. This is a common knowledge. Of course, many do surrender in difficult situations, and we can't blame them. However, joining your enemy and helping the foreign power kill his own countrymen for his own ambition and glory? This is NOT acceptable in any country, at any time, under any circumstances. This, for a military personnel, is treason at the highest order.