[quote=@Jamesyco]Also entrenchments have always been used, even in the field of battle. During this age of revolution, they were really put into full potential. Waterloo, the different riots in Paris, Yorktown, Borodino. Most of the time, the two armies would entrench and fight over several days while marching troops across an open field littered with bodies of previous waves of men while being fired upon. Sometimes they would meet the enemy out in the open if both armies sent out men at the same time or sometimes as a quick counterattack if their line won the skirmish. [/quote]
You are correct about the accuracy. A lot of soldiers in the line did not want to kill another human and would aim high or low. When You read historical data on the subject, the empiricist does not state why the units miss, just that they miss. There was an experiment done in the UK using smooth bore muskets. They found that a battalion (~1000 men) would hit roughly 60% of their targets when firing at hay bales. But as described during the conduct of battle when there was the potential for shooting at humans, committing a sinful act or placing oneself in harm's way, the accuracy dropped to about 3-6%. The bayonet was the primary weapon on the battlefield.

Building a redoubt with a trench circling a built up area surrounded by wooden pikes or palisade was more common than fighting in an actual trench. This forced the enemy to climb the banking of the redoubt from the trench up the wall and past the pikes.