Sickles was correct about his originally assigned position being weak, certainly it was weaker than the higher ground along the Emmitsburg Road. If he stayed put and Longstreet had launched his attack as he did, there would have been no need to divert troops along the path, which means, for one thing, Law's brigade would have remained together and swept over Big Round Top, well beyond the Federal left. Artillery at longer ranges was ineffective, and in addition there were ample woods to protect most of Longstreet's force from all the guns the Federals could muster on Cemetery Ridge, and good positions for Sickles' artillery were lacking at his originally assigned position. The Fifth Corps, presumably thrown in then to bolster the Federal left, would have engaged Longstreet's men as they held the summit and open ground east of Little Round Top, which was somewhat in rear of the main Federal line on Cemetery Ridge - not good for Federal morale, especially as Anderson would be attacking them in front. The Confederates would also control the Taneytown Road, leaving only the Baltimore Pike open as a potential escape route, and that would tend to make all of the Federals nervous. In fact the Sixth Corps might have been held in place on the Baltimore Pike as a precaution, especially since Johnson's Division would soon threaten the opposite end of the line. At that point Federal troops in the center of the line would hear heavy firing both in their left rear and their right fear - that would get the attention of even stalwart veterans. We know what happened when Barksdale's brigade slammed into the stronger Third Corps position at the Peach Orchard; if they and their companions had done the same thing north of Little Round Top, the bulk of the Union army would be threatened with panic and subsequent annihilation.