The Peloponnesian War began after the Persian Wars ended in 449 BCE.
- The Washington Naval Conference was a Conference that gathered the world’s largest naval powers. The main objective of the Conference was to discuss the naval disarmament and ways to relieve the tensions in East Asia.
- The Nine-Power Treaty was a treaty that was signed in the Conference, it internationalized the US Open Door policy in China. All countries that signed it would respect the integrity of the territory of China.
- The Kellogg-Briand Pact was a multilateral agreement that attempted to eliminate war as an instrument of national policy.
All of those have in common the aspect of a multilateral agreement between countries that attempts to avoid war and also protect other countries sovereignty.
B, the courts.is the answer
Under the feudal system, lords provided vassals with fiefs (which were pieces of land) in exchange for military protection, loyalty and support. In order to do their duties and obtain the priviledge, vassals had to swear on oath loyalty to a particular lord at a feudal ceremony.
