The Confederate attack on Parson's Battery was a difficult one, but they would eventually take the position. In the slight valley between their jump off position and the battery was a fence line that caused them some problems. It slowed the assault and was well within artillery range. Here's a view along a reconstructed fence.
And the view from the same spot looking up the hill at the battery.
A different sort of cannonball now litters the field. At Chickamauga earlier that week (this picture was from my fall 2006 trip) one of these had fallen on top of the truck cab and severely startled me. Luckily it didn't dent the truck.
As you can see here Parson had great fields of fire and would have been able to blast any approaching infantry. The fence line can be seen just over the end of the cannon barrel.
Once Parson's position was captured the Confederates found themselves with a new problem: a new ridge line behind Parson that would soon be called Starkweather's Hill. Despite being generally out manned and outflanked in key areas the Union was able to cobble together a pretty good defense because they always seemed to have another ridge line to fall back to.