How do I Crusade?

[Prussian to the Iron]

You don't really need to put them on a ship. I've sent a crusade overland from Caen to Antioch with no ill effects to my relations with other catholic factions. As long as it continues moving towards the goal, you don't get any desertions either.

unfortunately this is really the only way to do it from England; i once tried to sai a crusading army from london to Jerusalem, and somehow people still deserted, even when i was just trying to sail around france.