Question about spy defense against revolt

[Taurean]

Playing on hardest, running communism.

I had a city with about 7 spies in it, most of them veterans. It was just taken over by an enemy diplomat by inciting revolt, resulting in me losing my entire attack force and about 1000 shields worth of production. Including all my spies.

I thought that having spies in a city defended against enemy spy and diplomat influence?

 

[Prof. Garfield]

I think diplomats and spies only defend against technology theft. Democracy is the only sure defence against bribery. I don't know how the AI responds to a large treasury or the presence of a courthouse.

 

[Versius]

I think diplomats and spies only defend against technology theft. Democracy is the only sure defence against bribery. I don't know how the AI responds to a large treasury or the presence of a courthouse.

That is correct, they may also make it harder to sabotage and/or poison the water supply. I am not sure if they might raise the price of revolting a city. I am currently working on taking a city but the price to buy the city is just unreasonable, +$5000. So, I have been sending in spies to poison the water supply taking the city from a population of around 18 down to a 12 and it is much more affordable now. I was also able to use a similar strategy to damage an enemy civ by severely poisoning troop production cities. I also destroyed all of the happiness improvements in a few important cities making it impossible for the civ to maintain Democracy. Thereby disrupting the war effort and making bribery possible.