I'm confused as to why they went back to line firing and just walking straight into the enemy, even into artillery fire. When they fought the revolution war, they used guerilla warfare that was very effective. So why did they go back?
To make a long story short, the premise of your question is incorrect. Both sides employed guerrilla warfare during the revolutionary war, but the heavy lifting was done by regular soldiers.
u/bacarruda wrote an excellent post on the subject here.