Why did churchill replace chamberlain as britain's new prime minister shortly after world war ii began?

the excerpt from chapter 2 of "animal farm", by george orwell that is an example of foreshadowing is "these three (snowball, napoleon, and squealer) had elaborated old major's teachings into a complete system of thought to which they gave the name of animalism." animal farm is an allegory of how czarist russia developed into communist russia with all its corruption. old major's teachings represent marx's theories turned into communism, animalism, by the three pigs. this foreshadows the oppression and corruption that will follow this revolt.

i'm going to go whit a