For his part at the end of Day 2, Meade had presented three courses of action to his staff: withdraw, attack, continue to defend. Almost to a man they recommended the latter. His J-shaped position was strong and well-placed. They saw no advantage to either of the other options. All of his 70,000 or so infantry were in place. There was nothing more to do than wait and react accordingly.
Just after noon of Day 3, Lee unleashed his 120 cannons on the Union defenses. For over an hour, they fired thousands of rounds – many of them the fused shells – across the one mile gap between the lines. The smoke of the propellant gun powder prevented the Confederate officers from seeing the target much less assessing the damage they were doing. No sooner had Lee’s barrage begun than it was answered by the Union, who had a similar number of cannons but arrayed over much greater distance; many out of position and out of range of Pickett’s charge. One astonished Union officer observed that 9/10ths of the shells overflew their targets and continued on into the interior of the ‘J’. Shells began to explode near Meade’s HQ to the point that they thought that they were somehow being directly targeted. At the urging of his staff, Meade shifted his HQ farther east.
It didn’t take long for Meade’s forward commanders to assess Lee’s plan. They knew an infantry attack was going to follow the artillery barrage intended to soften up the defense. To lull the Confederates into thinking that their plan was working, they ceased their cannon fire as if to suggest that they had withdrawn. And then they waited. Because the artillery were indeed placed behind the infantry, they had taken heavy hits from the late-exploding shells. One unit was so badly destroyed that it withdrew towards the interior. Through the haze of gun smoke, Rebel Artillery officers spotted this movement and determined that they had successfully destroyed the defensive line. It was time to cease fire and let the infantry advance.
Meade had some 120 guns aimed back at the Rebels; 29 of them in the cemetery alone. But BG Hunt, Meade’s Artillery Commander, had cautioned them against wasting ammunition on counter-battery fire. After all, they were essentially firing blind at the distant hill without being able to see many of Lee’s guns. Once the smoke enveloped them, they were truly blinded. Hunt told the batteries on Little Round Top to await the infantry attack that was sure to follow the barrage and not to waste ammo on counter-battery fire. It was partially this calculated lack of return fire that convinced COL Alexander that his barrage was more effective that is was.