They disappeared, I'm not jk I'm Fr
Answer: The Underground Railroad work by giving slaves and place to stay. The slaves went from house to house with a light in a window. Most of the houses had secret areas or false floors and carts. The slave would either get in one of the false floor area or get in the cart.
Harriet Tubman was the leader of the underground railroad. She would tell the slaves a certain time to go to each house.
It failed because China is a land of the proletariat and the ruling party is a communist one while the fifth modernization was about introducing democracy. Since the party represents the working class and the will of the people in theory, democracy is against it since it would enable those who are against the party to also compete which would in theory mean that they are against the people.
It drastically reduced the Jewish population in Europe and surrounding areas