Final answer:
Germany believed it was encircled by hostile nations and needed to be ready to fight them due to actual military threats, paranoia and misperception, diplomatic isolation, and fear of economic competition.
Step-by-step explanation:
Germany came to believe it was encircled by hostile nations and needed to be ready to fight them due to a combination of factors. One primary reason was the actual military threats from neighboring nations such as France and Russia. Germany faced a hostile France to its west and Russia to its east, which led to genuine concerns about its security. Additionally, there was an element of paranoia and misperception of geopolitical realities, as some German leaders believed that their nation was being deliberately isolated and targeted by alliances formed between other European powers. These alliances, such as the Triple Entente between Britain, France, and Russia, further fueled Germany's fear of encirclement. Finally, there was also a fear of economic competition, with Germany worried about the growing economic and military power of Britain, France, and Russia.