The alliances system meant that a local conflict could easily result into an intimidating global one. The overall cause of World War was the assassination of Archduke Franz Ferdinand. Nationalism was a great cause of World War one because of countries being greedy and not negotiating.
Your welcome I don't know if that helped. But yea.
The correct answer is "protection".
In feudal society, a vassal was a person invested with a fief for which they had to povide services to a lord. First, a feudal contract was made, and under that contract, the lord was bound to provide the vassal with the fief, i.e. to provide protection and to do him justice in court. In return the Lord could demand the services which were attached to the fief, and these could include all kinds of services - military, administrative etc.
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A
Is do not no if this is correct