Loss of biodiversity , soil erosion , water pollution and etc ..
Answer:
They feared that Catholic and Jewish immigrants would change the country's character and They distrusted people who looked different and couldn't speak English.
The world war two broke out when Germany invaded Poland. Britain and France consequently declared war on Germany to enforce the terms of the Versailles treaty. but they were already late because their appeasement policy had already served to militarize and arm Germany.