Q:

Effect of propaganda during the American War of Independence

In what way did propaganda play a part in the solidifying of American identity in the American War of Independence, and how was propaganda used by the British at home to generate support for the war?
I'd be particularly interested in any examples of propaganda media used by the actors in the war, and why. 
edit: Propaganda as published media intended to sway support to one side or the other.

A:

There are many examples of propaganda in the American revolution. A few that come to mind off the top of my head:

Common Sense, so beloved of grade school teachers and proto-communists everywhere.
Letters from a Pennslyvania Farmer Note well the list of several dozen similar propaganda vehicles cited at the bottom of that page
The correspondence committees - the US contribution to revolution world wide. These were crucial to the transformation of multiple independent resistance movements into a single coherent revolution.  

Another source you could consult is Gilder Lehman's lesson plan on propaganda
I realize that you asked about the effect of propaganda, and I've supplied an abbreviated list of propaganda publications, but I was interrupted while writing - I'll have to return to this later today.  (In particularly I want to find the propaganda written by a woman, because I think that is cool).   
Propaganda played a major role in unifying the colonies and in advancing the cause of revolution over negotiation.
I cannot bring to mind any British propaganda of the period apart from the song Yankee Doodle, which originally mocked the colonist's pretensions.  Certainly Ministers made statements and speeches, but those were not propaganda because they were intended to accomplish the governance function, not to persuade.  One could argue that the Intolerable Acts were a form of propaganda, but I find that a weak argument.  Franklin's appearance in the Pit was a form of propaganda, but it really just confirmed the opinions of those who held them, it didn't seek to change opinions.  (Perhaps North would have argued that it should have changed American opinions).  
There is probably another essay on British miscalculations which caused them to lose the propaganda war, but since I don't have time to write it, I'll refer to someone better than me who has already written it; the inestimable Mike Duncan, who in episode 18 of the Revolutions Podcast covered the ground.  That wasn't his core thesis, but I think he summarizes very well the reasons why the British failed.

A:

The middle of the 18th century was the height of the British nationalist movement. Examples of this movement include composition of Rule, Britiannia! and creation of the popular of cartoon character, John Bull. John Bull is a simple, jolly, content, country gentlemen who represents Britain and is often placed in opposition to France, Scotland or the popular American cartoon symbol of Uncle Sam. Uncle Sam may date back to as far back as 1775. He is mentioned in the song Yankee Doodle, which mocks American troops, but was later adopted by them. 

Old Uncle Sam come there to change Some pancakes and some onions, For 'lasses cakes, to carry home To give his wife and young ones  

The US developed the psuedo-classical goddess Columbia, which shared many characteristics to the British goddess, Britiannia. This helped create a national American identity by uniting the Old World and the New. Columbia has fallen out of use and has been replaced with Lady Liberty.
Columbia appears in the poetry of African-American Phillis Wheatley in 1776 during the revolutionary war:
One century scarce perform'd its destined round,
When Gallic powers Columbia's fury found;
And so may you, whoever dares disgrace
The land of freedom's heaven-defended race!
Fix'd are the eyes of nations on the scales,
For in their hopes Columbia's arm prevails.[7] 

A:

The Declaration of Independence was explicitly written as propaganda, to convince the World and its leaders that the actions of the American People were reasonable. Consider these excerpts:

We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness.--That to secure these rights, Governments are instituted among Men, deriving their just powers from the consent of the governed, --That whenever any Form of Government becomes destructive of these ends, it is the Right of the People to alter or to abolish it, and to institute new Government, laying its foundation on such principles and organizing its powers in such form, as to them shall seem most likely to effect their Safety and Happiness.
...
The history of the present King of Great Britain is a history of repeated injuries and usurpations, all having in direct object the establishment of an absolute Tyranny over these States. To prove this, let Facts be submitted to a candid world.
  - He has refused his Assent to Laws, the most wholesome and necessary for the public good.
  -  He has forbidden his Governors to pass Laws of immediate and pressing importance, unless suspended in their operation till his Assent should be obtained; and when so suspended, he has utterly neglected to attend to them.
  ...
  - He has obstructed the Administration of Justice, by refusing his Assent to Laws for establishing Judiciary powers.
  - He has made Judges dependent on his Will alone, for the tenure of their offices, and the amount and payment of their salaries.
  ...
  - For abolishing the free System of English Laws in a neighbouring Province, {note: referring to Quebec, which the Colonies would then attempt to conquer due to the intransigence of the native Habitants] establishing therein an Arbitrary government, and enlarging its Boundaries so as to render it at once an example and fit instrument for introducing the same absolute rule into these Colonies:
  ...
  - He has abdicated Government here, by declaring us out of his Protection and waging War against us.
  -  He has plundered our seas, ravaged our Coasts, burnt our towns, and destroyed the lives of our people.
  - He is at this time transporting large Armies of foreign Mercenaries to compleat the works of death, desolation and tyranny, already begun with circumstances of Cruelty & perfidy scarcely paralleled in the most barbarous ages, and totally unworthy the Head of a civilized nation.
  ...
  We, therefore, the Representatives of the united States of America, in General Congress, Assembled, appealing to the Supreme Judge of the world for the rectitude of our intentions, do, in the Name, and by Authority of the good People of these Colonies, solemnly publish and declare, That these United Colonies are, and of Right ought to be Free and Independent States; that they are Absolved from all Allegiance to the British Crown, and that all political connection between them and the State of Great Britain, is and ought to be totally dissolved; and that as Free and Independent States, they have full Power to levy War, conclude Peace, contract Alliances, establish Commerce, and to do all other Acts and Things which Independent States may of right do. And for the support of this Declaration, with a firm reliance on the protection of divine Providence, we mutually pledge to each other our Lives, our Fortunes and our sacred Honor.

