What Little round top commander who ordered a bayonet charge?

Colonel Joshua Lawrence Chamberlain of the 20th Maine Volunteer Infantry, who was then under the command of Colonel Strong Vincent, ordered a downhill bayonet charge against the Confederate 15th Alabama and, it is thought, elements of the 4th and 5th Texas, when his troops' ammunition was exhausted and they were facing another charge up Little Round Top (which, by the way, was not called that by the troops at the time; it was simply an isolated Union army Signals post before being occupied) by the Confederate infantry. The Confederates, also exhausted by their repeated uphill charges in the attempt to take the hill, and short on ammunition as well, were surprised and overwhelmed by the charge and were defeated, with many being captured, including their commander. It is believed by some military historians that this action saved the day for the Union army at Gettysburg, as the 20th Maine represented the "end of the line," the extreme left flank of the Union army, and had they been overwhelmed the Confederates would have rolled up the New York and Pennsylvania infantry also occupying the hill, and ultimately have threatened the positions at Cemetery Ridge and Cemetery Hill. Other historians dispute this claim, with some justification, given the ineffectiveness of the Confederate cavalry Corps, led by J.E.B. Stuart, for the first two days, due to vague orders given by General Lee to General Stuart, as well as the splitting of the slain General Thomas "Stonewall" Jackson's Corps into two Corps commanded by generals witb insufficient experience and initiative. It is left to the reader to make a determination as to which viewpoint is correct. It is the view of this writer that it was a combination of elements which led to the defeat of the Army of Northern Virginia at Gettysburg, and that the inability to take Little Round Top was not the signal failure which led to the ultimate outcome, but rather one of a series of elements which, taken together, led to the Union victory.