While Lords of EverQuest doesn't feature completely persistent units, you will be able to carry over certain members of your army from one scenario to another. At the end of each mission (assuming you win), you'll be presented with a nice little shopping screen. Here you can use points earned by completing the mission to pay to have specific units move along to the next scenario with higher level units costing more points than lower level ones. Extra points can be found by completing the two or three side quests each mission contains. Once you've paid to transfer your army to the next scenario, they'll form your starting force once the next mission begins.