Why did Americans choose not only to break from Britain but to adopt a republican form of government in 1776?

To understand the reasons why the Americans broke from Britain in 1776 look up the Declaration of Independence on the Web. There is the basic document consisting of four long sentences. Then there are the reasons. There is a long list. Read the list. The Republican form of government came about because the states wanted to cooperate. The logical form of government for the states to cooperate was a republic.