How did warfare and the constant threat of invasion in europe lead to the creation of feudalism?

What is the name for the main idea behind the settling of western lands by americans in the early-1800s?

Why was the united nations established

By the late 1930s, how were u.s. officials beginning to view japanese policies of expansion? a. they attempted to join forces with japan so as to increase u.s. territory. b. they warned them to stop expansionist actions or face potential u.s. intervention. c. they sent representatives to japan to work out territorial rights in a diplomatic fashion. d. they became fearful of their military power