Did the FBI have a warrant to spy on the CIA spy Patreaus?

No. Many people work for the CIA or FBI as analysts, payroll, secretary, human resources... Those people do not have to keep their professions a secret. The people who DO keep it a secret are CIA field agents who may or may not go to a foreign country and work in covert operations or FBI agents who work cases that involve them going undercover to try and prevent crimes or capture criminals.

Many times, CIA agents who ARE spies are commonly placed in a diplomatic unit where its easy for them to be in a foreign country and not arouse suspicion. Spies can be diplomatic couriers or pretending to be a diplomatic official (case in point: Valerie Plame who was outed by the Bush White House as retaliation against her husband (Ambassador Joseph Wilson)...her non-official cover at one point while with the CIA was as Junior Consular Officer when she was in Athens).

Hint..the FBI...specifically their counter intelligence people.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.