The south— the north (mostly) opposed slavery, whereas the south (mostly) wanted to keep it around. In fact, slavery was one of the main reasons the American Civil War was fought in the first place.
The red guards carried out the cultural revolution by persecuting intellectuals and government officials
One country led by religious group is syria
The tiny invaders being discussed in the article are plants. They are considered invaders because they came from other countries, but are now threatening the native plants. People brought them in because they wanted to make their gardens and yards beautiful because the plants are very rarely found locally.