RTFM or let's read the C4C manual, more precisely a section about privateer. C4C manual p.31: The Privateer: The Privateer is a special kind of naval unit designed to allow one to harass foreign shipping without necessarily going to war with the foreign nation. Privateers move, carry cargo and fight like other naval units; however, Privateers are issued "Letters of Marque and Reprisal" and do not fly under a national flag: therefore they can attack foreign shipping without triggering war. In other words, you can purchase or build a Privateer and send it off to attack your opponents and they wont know whos behind it. Note, however, that all navies consider Privateers hostile, and theyll attack em on sight. Remember that Privateers can capture cargo from defeated cargo vessels too; see above. And above in C4C manual p.30: Privateers: When a privateer defeats a cargo vessel, it captures a portion of the defeated vessels cargo. Well, as you see, the privateer can captures only a portion of the defeated vessels cargo. However, a lot of immigrants from Europe travel to New World on transport vessels, too. What's happen with them when a privateer defeats a transport vessel? According to current game's code all immigrants must die. It's rather bloodthirsty, isn't it? Such situation could be very easily corrected. Open in Notepad file "CIV4UnitInfos.xml" and find a <Type>UNIT_PRIVATEER</Type>. Add in the section: couple new lines: Now your privateer can carry units (immigrants) as well. When a privateer defeats a cargo vessel, it captures not only "a portion of the cargo", but also the travelling immigrants from the defeated vessel. Such privateers are very effective especially on early stage of the game. Two-three privateers can fully block the connections of your opponents with Europe. Moreover, you could capture not only quite cheap and small cargo (in the beginning) but also your opponent's immigrants that are very valuable and "must have" as soon as possible.