LOL? Im pretty sure the Romans (Citizen and military) were overjoyed all across italy when they heard Carthage fell to their boys.
Or when the Greeks drove back the Persians? They built monuments about that victory. I know the Greeks were seperate at that time and its not right to call them a nation, but when they heard Persia had been defeated at Thermopylae and Platae all of Greece rejoiced, save for the ones who fought with Persia
Alexander conqureing Persia? He became the greatest conqurer of all time after his campaign. Theres monuments everywhere that show nations coming together to rejoice their recent victory so i dont understand your statement at all.
So i agree with the op that there should be a national morale increase or penalty for certain defeats or victories.