"Great Merchants" provide the goods and services civilizations need to survive. They import food, medicines, and luxuries, and they export a civilization's manufactured goods. They provide the financing needed for great works to be accomplished. They create a civilization's wealth.
Strategy[]
Besides constructing the special Customs House improvement which, when worked, produces loads of Gold, the Great Merchant can also journey to a city-state and perform a "trade mission" which produces gobs of Gold and gains many points of Influence with the city-state. The Great Merchant is expended when used in either of these ways.
Again, you have the choice to use it for a long-term boost of the Gold production of one city (choose this city well), or use its unique ability to get a large one-time boost of Gold and Influence with a City-state. Note that the Trade mission may sometimes prove dangerous, especially if the City-state is far away.
Generates less Influence and Gold when completing a Diplomatic Mission with a City-State.
Cannot be used to build a Customs House.
May be purchased just as any regular unit.
Can be upgraded at the cost of Gold into a Great Ambassador, which is twice as influential at performing Diplomatic Missions as a regular Great Merchant.
Great Ambassadors may also be used to acquire a City-State outright, bringing them under Holy Roman control as a puppet.
Can costruct the Custom House or perform Trade Missions, but upon being expended in any of these ways, Trading Posts are automaticly constructed in all adjacent unimproved tiles, even if the required technology has not been researched.
Generates bonus Influence from Trade Missions, scaling based on distance from the Capital
May be expended in the territory of another Major Civilization to conduct a Diplomatic Mission, providing a burst of Influence with every City-State allied to that civ
Custom Houses created by Utusan claim adjacent Coastal tiles.
If inside the territory of a city-state, nearby combat units may pressure the City-State into allowing tribute much more effectively. This can be repeated with each city-state further away from the Capital than the last.