The colonists at Lexington and Concord were alerted that the British were going to confiscate the colonists weapons when they arrived so they fought due to the fear of the British gaining leverage on the colonies by disarming them
Truman put limits on MacArthur because Truman was not happy that MacArthur moved to north of 38th parallel.
Also,<span>MacArthur rejected the idea of peace negotiations and he was very arrogant.
Hope it helped.</span>