1. They didn't want to be taxed anymore. They had no representation in British parliament and thought it was unfair to be taxed if they had no say in what or how much they were being taxed in.
2. The Boston Massacre brought together the colonies after British soldiers killed five innocent colonists. This created a lot of tension against the British and the colonies but overall brought the colonies together stronger.
3. Start of the American Revolution. The colonists knew that if they wanted to be independent by themselves without Britain they had to remain together and be strong in numbers, as Britain had more numbers and weapons as they did. Their want for independence and the hate of Britain brought them all together.