This panel includes reference to the Tax Act, the burning of tax stamps (1765) and colonists listening to a fiery unidentified orator, part of the protests against the cry of “taxation without representation.” 

The upper left depicts the Boston Tea Party (1773) when the Sons of Liberty disguised as Native Americans dumped British tea into Boston Harbor to protest the tea tax. 

Next to this is the Boston Massacre (1770) when British troops fired into protesting Americans, killing several. In the center five working class men, one a person of color (perhaps a reference to Crispus Attucks, the first man killed in the Massacre), prominently raise a flag of the new republic. (The flag with the stars and stripes was first raised in Philadelphia in 1777.) 

Washington appears at the far right taking command of the Continental Army (1775) to cheers.