1. to spread christianity
2. they thought that they could become wealthy
Artisans organized medieval crafting guilds for a very good reason - it was mostly because it benefited themselves. They found out that if they stuck together and helped each other out in certain times, it was beneficial for them as they could earn more and have less "stress" with not having jobs or enough equimpent or knowledge.
In a long period of severe heat or cold, most of civilians had a really rough time in obtaining foods to feed their families.
Under such conditions, people will have a greater tendency toward violence as a desperate attempt to survive.
Because of this, more wars and rebellions tend to happen within long period of sever cold or heat.
