Defining a "pitched battle"

I had always assumed that a "pitched battle" was a heated or intense confrontation.  That indeed is the second definition, but the proper use of the term refers to more specific conditions:

A pitched battle is a battle where both sides choose to fight at a chosen location and time and where either side has the option to disengage either before the battle starts, or shortly after the first armed exchanges.

A pitched battle is not a chance encounter such as a skirmish, or where one side is forced to fight at a time not of their choosing such as happens in a siege. For example, the first pitched battle of the English Civil War was fought when the Royalists chose to move off an escarpment to a less advantageous position so that the Parliamentarians would be willing to fight the Battle of Edgehill. In contrast the Battle of Gettysburg, fought during the American Civil War, started by chance as a skirmish, but as both generals chose to reinforce their positions instead of disengaging, they turned what was initially a skirmish into a pitched battle.