It's a fairly short step from pilgrimage to war at times:

http://turba-delirantium.skyrocket.de/bibliotheca/walther_vogelweide_palaestinalied.htm

A very frequently performed song but I've never heard anyone sing all of it, verse 11 included. The point of it was to be a rallying cry, and it leads up from the mystical ecstasy of the opening to the "kill 'em all and let God sort 'em out" sentiments by a brilliant series of dialectical steps. It is both one of the most evil pieces of propaganda ever written and a work of genius.