Bernhard, that's helpful, thank you. This explains why I've seen photos of "Panzerartillerie" that is towed by horses...
As for "indirect fire" with the StuG... That had to be difficult considering the gun carriage. Actually, tanks usually train in basic indirect fire and artillery trains in direct fire; the opposite modes of usual fire - for emergencies. Artillery in direct fire is usually for battery defense, but I've actually direct fired 155mm shells into log crib obstacles...very effective demolition.