Answer:
The American colonies did not wish to gain independence from Great Britain for a very long time. In fact, even after all the grievances and sufferings of the people and the land, caused by the abuses of the British, Americans did not decide to support the cause of independence until the Revolution was pretty much under way.
However, grievances, and trouble, started piling and piling, and even though the colonists attempted all within their power to change things and solve their issues in a pacific way, the King, George III, did not respond accordingly and fueled the desire for final independence.
In this particular excerpt, we see the sufferings of the colonists, and how long these sufferings have been going on, when the excerpt says: "Such has been the patient sufferance of these colonies..." Just this first line shows, first, with the use of such a strong word as "such", that things were going really bad. Second, it shows that peoples´ patiences were tried when the government did not respond as it should have. It was this, the long wait for solutions that never came, and the lack of action from the British King, that finally convinced Americans that they needed to alter what had once been sure to them. They chose independence.