If I recall, the original question was "How do I crusade?", yes? If so, to have an army join the crusade you must have a general/family member leading the army. If you right-click on their portrait, there will be a button on the bottom of the scroll that reads "Join the crusade." Push this button and your units will turn dark turquoise-like and a white cross will appear on their unit cards. In addition, your recruitment queue will have new units to recruit, ones that are specially designed for the crusade. And finally, your general (on the campaign map) will have a red cross on top of his banner. If you take the targeted city, you will be rewarded with florins and upgrades for 20- 30 units from the pope