The Indies Run Event:
https://es.wikipedia.org/wiki/Flota_de_Indias (sorry did not found a version in english)
https://en.wikipedia.org/wiki/Manila_galleon
Since XV century till XVIIII spanish empire created a system of convoys that departed every year from the Caribbean capitals to the Homeland. These were charged with goods and specially gold and silver. The departure dates were always a secret, and of course all type of pirates and enemy fleets tried to intercept them
Idea is to Add more dinamic event to the game
Once per week an anouncement is made that rumours of a large fleet is going to leave from a random port (but unknow). Only clan leads owners from the given source and target port are notified on the details of the trip (date, hour, destination) . Along the week, any sunken/captured trader ship from the fleet faction may contain a note with either : departure port, or date of departure, or hour of departure, or destiny port.
The day of departure , a large fleet composed by warships and merchants will leave the origin port at the given hour, will make the trip to the target port. Fleet may be composed by several squadrons travelling separated.
Clan friends from the origin//target port owners of the fleet may defend it , players from the other clans may try to destroy/capture it, ships from the fleet will try to escape from battles and continue travel.
Benefits for the fleet defenders: the port where the fleet departs will receive a temporal bonus during X number of weeks (labour hours reduction, or less taxes) , destination port may receive also bonus (boost on dropped items or even new products that normally only drops on the origin port). As probability that the fleet arrives sound and safe diminishes the closest to the target port, the benefits would be given in a % depending on the total of kms sailed and the number of ships that arrive with their cargo.
Benefits for the fleet attackers: the traders will be loaded with valuable goods (ingots//doubloons) , so the attackers will have to combine fighting against war ships and capturing the traders. For every enemy ship sunken or captured on the battles, the attacking players would receive combat medals or victory marks...