The action that completes the diagram is:
British ignore colonist grievances.
Following the British Constitution, Britain was not allowed to taxate its subordinate colonies without the approval of their representatives in Parliament. But the problem was that these colonies in America were no represented and still had to pay for taxes imposed on them. Soon they clung to the motto "no taxation without representation". This eventually increased tensions between the two and led to the American Revolutionary War (colonies vs Britain), which resulted in the Declaration of Independence.