The answer is: Political bosses expanded their power by helping immigrants in return for their loyalty.
At that time, many of the political bosses realized that if they somehow can help the immigrants obtain their citizenship, the immigrants will become much more likely to return their favor.
This mean that they can influence the immigrants to vote for them during the election in exchange for the citizenship. This help the political bosses expanded their power.
It's a thing called "scorched earth". the russians would rather burn their fields and slaughter livestock to the ground than have the french successfully take over their houses and farms and eat and steal their food, etc. it's a way to let the french starve!
The answer to 10-(-12)/4 x 3 = 19
This question belongs in a philosophical debate, it is one of those questions that everyone in the world has a slightly different answer to.