The British abandoned Boston in early 1776 because they were forced out of the country by the American soldiers.
American Revolutionary War was at large, and the Patriots, led by general Washington (who later became the first president of USA) won the battle at Boston, which was bloodless, by the way. This brought an end to an eight-year British occupation of the city.
Eastern Europe I think.... not 100% sure
It benefited in numerous ways but mainly it and maybe most importantly it gave them the access to the China trade. The Pacific route was also Spain's exclusively for a certain period of time and there was also a great need for silver in China which was supplied by the Spaniards from their silver mines.
