Meaning, you cannot line up to build a bunch of dwellings with one unit. Problem is though unlike some games, you cannot build more than one building at a time with the same serf. Building in the game is quite neat as more than one serf can work on a building at a time. It's quite appealing and makes it extremely easy to line up and manage units. Until someone for themselves see how this system works, it becomes a game of "line up my armies behind one another". Other units can be told simply to line up or square up accordingly.
Units can be given a drummer and an officer and be given certain formations. One of the main features in this game that surpasses other RTS's is the unit organization. The ship battles are just as intense as the unit battles. If there is water present, the user can build shipyards and amass some major galleys or frigates. Priests and the like heal other units, archers to musketeers are available for range, ground units can be swordsmen to horsemen who ride extremely fast. Different units obviously offer different strategy. The unit types are various, from priests, to serfs, to mercenaries, to drummers, to officers, to musketeers mounted on horses. They've done a great job to differentiate the different races within the game as not all units look the same.
I've put over 100+ hours into this game before purchasing it on steam (I lost my CD)! There is a lot of complexity that can go on within the game, and really gives the player a sense of creating a city. Cossacks : European Wars to me is one of the greatest RTS's ever made.