Welcome to another development diary for Europa Universalis. We finally announced Mare Nostrum earlier this week, and today we’ll talk about a few more features for it.First of all. We’re adding Trade Leagues to the game. There existed a feature with the same name in EU3, but this is radically different.Any Merchant Republic can create a Trade League by inviting other countries to it. However, only countries with 1 province can be a member of a trade league, excluding the leader.. Only a merchant republic can lead a trade league, and if the leader is annexed, another merchant republic in the league takes over leadership, if no new leader exists the league is disbanded.Members get a small relation bonus with all other members, and the trade league is a defensive alliance between all members, and will consume one diplomatic relation. All members automatically embargo anyone the leader embargo, without a penalty.If any members in a league gets embargoed, the leader gets a casus belli on the offending party.Trade league leaders automatically have a trade dispute casus belli on any countries they would be able to generate such a casus belli on via spy action. That Casus Belli has been changed so that it is not possible to take territory, return cores, cancel vassals or release countries when using it.The Leader gets 50% tradepower from all its members, and it gets a nice bonus to trade steering that is based on the amount of members in its league.The members also have the following benefits. Doubled bonus on goods produced from the leaders merchant republic ability, and a +20% tradepower bonus on its ships. A member can leave a league at any time.Another part of Mare Nostrum is a greater control of Mercantilism. Now you’ll be able to increase your mercantilism at any point you have enough diplomatic power. Of course, there are drawbacks to mercantilism, in that the more you have, the more money is lost through corruption.One aspect of the trade system in Europa Universalis has been how powerful a trade-network could become, and especially where a nation have basically have a monopoly. So one of the major tweaks in 1.16 is that the more monopolised a node is, the more effective pirates are there. When the leading power in a node has 100% of the tradepower there, then pirates will have a 100% power increase. Of course, if there are privateers in that node, then they reduce the power of the monopoly…Next week we’ll be back with a diary about the new naval mission system, naval combat changes, naval leader enhancements and other naval improvements.