# they answer peaceably

Possible meanings are 1) they answer in a peaceful manner or 2) they accept the offer of peace.

# open their gates to you

"let you enter their city peacefully". The phrase "open their gates to you" represents the people surrendering.  

# all the people who are found in it

"all the people in the city" 

# must become forced labor for you

"must become your slaves"