1775:    A Good Year For Revolution, by Kevin Phillips

Among many other points, explores the aftermath of Lexington and Concord.   " The First Continental Congress had specified that the other colonies' support for Boston....would depend on the British being the aggressors". The Patriots were aware of this and acted immediately, sending the news that this had been the case , "prefaced and packaged" on a chain of couriers and fresh horses, Massachusetts to Georgia, with newspapers along the way "embroidering the apocryphal details of atrocities".

In addition, they sent the news on a fast schooner to London so that it could--and was--published in quite a few newspapers there.

They were determined to win the propaganda war on this. And they did.

General Gage sent a terse report-- stating that the Americans had fired first-- which arrived weeks later.   By that time quite a few Britons did not believe him.

It is actually unclear who fired first.

Now, according to a friend of mine who visited Lexington just recently, Lexington is perfectly fine with the idea that the Americans fired --"the shot heard 'round the world"---first.