Reference from
my guide for France:
Being unable to compete enough wonders nor having a great location for Chateaux? The AIs are proceeding tech and Civs like rocket? Don’t worry, its not the end of the world. CdM still has tactics under sleeves. Here we have the magnificent great work thieves spies to help. The scouting in previous eras now yields to give a list of enemy cities for us to exploit.
Espionage is the core of everything in higher levels from immortal. AIs will enter atomic era while we are still struggling with industrial wonders. Forget the wonders if we want to target an immortal victory. Thus a group of well trained spies will be a matter of life and death.
Our first spy comes at castle tech, with a free promotion. Depends on what promotion she (CdM’s spies are all lady in waiting) has, we shall assign her to different posts. The promotions in yellow are essentially powerful.
Ace Driver : Make her do anything you want. She will be safe.
Cat Burglar: Make her steal Great Works. Highly recommended for France.
Con Artist: Make her Siphon Funds
Covert Action: Make her Foment Unrest
Demolitions: Sabotage Production
Disguise: This promotion should be taken in later game, not now
Guerilla Leader: This promotion is less useful, at least not now.
License to Kill: Make her Neutralize Governor
Linguist: This promotion should be taken in later game, not now
Quartermaster: Make her stay in base for counterspy
Rocket Scientist: This promotion should be taken in later game, not now
Seduction: Make her stay in base for counterspy
Smear Campaign: Put her to CS and wipe out your foes’ envoys.
Technologist: Make her Steal Technology.
Because we only have one spy for instant, it is better to gain resources before executing any real mission. Our current aim is to train our lady in waiting to a master spy with the yellow promotions and prevent her from being discovered.
In R&F, every level of visibility to a foe will grant +3 combat strength to military units. Therefore, if we sense that war is to come, we should send a lady-in-waiting to operate "listening to post" prior to a DOW. That should give a slight but important difference in defense. (+6~+9 combat strength in total).
Quartermaster is among the most powerful promotions here. It can boost every spy operations by 2 level, rendering all specific promotions less necessary, other than linguist, and ace driver. But in these early days, no one else owns a spy. Therefore, we’d better try offensive operations first. The intelligence agency in government plaza is a bread-and-butter to spies missions too. Make sure that we build one when we are not busy with wonders.
Foment unrest allows spies to lower enemy city loyalty. But flipping cities is not that easy in most circumstances and we don’t have proper siege technology to grab free cities (it is away from both military science and flight). Thus flipping cities is not encouraged now. This mission can instead be a step-stone to train the spy for other useful promotions.
We can build 2-3 spies in the mid game. Once a spy has the quartermaster promotion, place her in a home city. Then use the other spies to target enemy’s cities to steal great works and syphon funds. Check who is currently leading cultural on the leader-board. Then check if there are great works steal-able in their cities. Some AIs may be willing to trade their great works with 400-500 gold, so syphon funds is a feasible way to earn more. (lol we use the gold stolen from them to buy their great works, such a marvelous deal.)
Kongo and Russia are the 2 civs that have very high possibility in owning great works.
Try to scout all of their cities and target them as priority.
Please take note that spies missions have a fairly high chance to fail and this will make our lady-in-waiting killed or imprisoned. Being killed is fine, as we just need to build another. But if she is captured, we will need to pay ransom to redeem her, or else we will have a non-functional occupied spy slot.
Moreover, this will harm diplomatic relationships. If this happens to our enemies, its always okay. But if this happens to a befriended civ, this could cause trouble in future attempts to fix the relationship, risking a breaking in alliance/ potential invasion.
If there are 4-5 great positive (green) diplomatic modifiers but only 1-2 little negative (red) diplomatic modifiers, its still worthy to risk it. Even if the spy is captured, a friendly civ will offer a lower price in redeeming the spy. Choose "ignore request" to minimize the impact of spying on alliance.
After we have got enough promotions, we can do whatever the condition demands to fit our goals.