GETTYSBURG -- Gunshots rang out, then full volleys, like the sound of ripping sheets, followed by the boom, boom, boom of cannon fire.
Across steamy, sun-drenched farm fields outside Gettysburg came waves of gray-clad soldiers, pressing steadily toward a thin blue line of Union troopers that slowly gave way.
On Thursday -- Independence Day -- a great clash fought here 150 years ago raged again, much to the delight of thousands of people watching from grandstands, picnic blankets, and folding chairs.
The reenactors and spectators came from all 50 states and at least 16 foreign countries to remember and re-create a pivotal fight of the Civil War that forever left its mark on this Adams County crossroads town.
They watched men fall in battle and clouds of gun smoke billow across the landscape. And they heard horses thunder by while officers shouted commands barely audible over the battle's din.
"What happened at Gettysburg was remarkable, and to see it live is an incredible show," said Mark Miller, 50, a physician from Delhi, Ontario.
"You can read history, but here you see it and realize how mistakes were made," he said as artillery roared nearby.
Thursday's reenactments, at 11 a.m. and 6 p.m., covered the first of three days of the Battle of Gettysburg and set in place the battle lines for the second and third days of the clash.
"I can't imagine missing this," said reenactor J.R. Schroeder, 49, a Union officer who lives in Detroit and three of whose ancestors were in the Army during the Civil War.
On July 1, 1863, the Confederates were spoiling for a fight. The sun broke through the clouds at 8 a.m. that day and shone off thousands of musket barrels along Herr Ridge, just outside Gettysburg.
Southern Maj. Gen. Henry Heth looked down at Willoughby Run and up to McPherson's Ridge, then ordered the advance.
By 9 a.m., the sparsely manned Union line began crumbling like a weakened dam against a Rebel force more than twice its size. And at 10:10 a.m., Union Brig. Gen. John Buford sent an urgent message to Gen. George G. Meade, the commander of the Union army moving on Gettysburg: "The enemy's force are advancing on me at this point and driving my pickets and skirmishers very rapidly."
As musket and cannon fire grew more intense, Maj. Gen. John F. Reynolds rode up at a fast gallop in advance of approaching reinforcements.
"What's the matter, John?" he asked.
"The devil's to pay," Buford said.
Reynolds, a Pennsylvanian, promptly assessed the situation and sent a note to Meade saying he would hold the enemy "as long as possible."
The meeting would obviously never have happened in 1863.
But 150 years later, Union and Confederate officers gathered under a tent in the Southern camp, where they bent over a large, color aerial Google map to discuss the positioning of blue and gray troops and artillery.
"Don't worry about our guns," Confederate artillery Col. Tom Alexander of Street, Md., told a commander.
"We're here to support you," said the Harford County, Md., sheriff's officer.
"No, you're not," quipped Union cavalry officer Doug Nalls, 50, of Winchester, Va. "You're here to kill me."
Nalls, a construction equipment operator, is usually a Confederate cavalryman, but was "galvanized" Thursday for the first day's battle, switching sides to build up the number of Union cavalry, which had a bigger role in the first day's fighting.
"Most cavalry troopers carry two uniforms" so they can reenact as a Union or a Confederate soldier, said Jim Ranke, 64, a Federal cavalryman who also lives in Winchester. "We do it to make a better appearance. I do it reluctantly."
"Today, if I was a Union soldier, I'd know we have a tough fight ahead of us, and some of my buddies would die."
Even in the bloodless reenactment, the reenactors get a sense of what the real soldiers experienced.
"When you see the overwhelming numbers of the other side, you can imagine the sinking feeling the Union soldiers had," said Federal officer David Shuey, 57, a first-person portrayal artist who lives in Newville, Cumberland County, Pa.
Columns of blue-clad infantry arrived just in time and moved quickly toward McPherson's Woods to shore up the collapsing Federal line.
Just then, the rebels struck -- and soon realized they were not fighting troopers but the Iron Brigade, infantrymen known for their grit, coolness under fire, and black felt hats.
"There are those damned black-hatted fellows again!" shouted a Confederate. "T'ain't no militia!"
Reynolds anxiously was watching the battle and urging the troops, "Forward! For God's sake, forward!" when a skirmisher's Minie ball caught him behind the right ear.
"He fell dead in an instant without a word," Union Gen. Abner Doubleday would recall.
One of those watching the fighting stood out from the crowd if for no other reason than his head gear. Mark Brandt, 51, of Anderson, Ind., wore a Civil War diorama on his head, complete with blue and gray soldiers, a stone wall, and trees.
"I love history, and I have never been to Gettysburg," said Brandt, a Army veteran of Desert Storm, as cannons blasted in the background. "I drove 1,600 miles to get here. This is so amazing."
Nearby, Dylan Rains, 8, of Rancho Cucamonga, Calif., sported a kepi and sword, courtesy of his father, who had pushed him into coming to the reenactment.
"I love the Civil War, but I probably wouldn't do this if it wasn't for my son," said David Rains, 48, an Army veteran and employee of a papermaking company. "He's the whole reason we're here."
The vicious fighting of the first day continued until about 11 a.m., when an uneasy lull settled over the battlefield. Soldiers on both sides swarmed over the landscape, preparing for the next round.
After noon, the Confederates renewed their attack with fresh troops, this time flanking the Union forces. The Iron Brigade, supported by some artillery, tried to hold back the gray tide.
One gunner said that "for seven or eight minutes ensued probably the most desperate fight ever waged between artillery and infantry at close range without a particle of cover on either side . . . bullets hissing, humming and whistling everywhere, cannon roaring; all crash on crash and peal on peal, smoke, dust, splinters, blood, wreck and carnage indescribable."
Eventually, the Union line was forced to pull back to trees near the Lutheran Theological Seminary on Seminary Ridge and then through town, where thousands were captured. The survivors later retreated to Cemetery Hill and Cemetery Ridge.
When the reenactment ended and the smoke cleared, a crowd of thousands erupted in applause and cheered Yankees and Rebels.
They had filled a large grandstand overlooking farm fields that had become a sprawling amphitheater and history classroom.
Many reenactors had traveled thousands of miles to give their history lesson. Confederate Jack Eaves, 56, a retired timber industry worker, drove a Whitworth breech-loading artillery piece from Eureka, Calif. "I built it from the ground up," he said.
Long into the night of July 1, 1863, Gettysburg residents heard the pitiful cries of the wounded and dying. Fifteen-year-old Tillie Pierce described what she saw at a barn:
"Nothing before in my experience had ever paralleled the sight we then and there beheld . . . We were so overcome by the sad and awful spectacle that we hastened back to the house, weeping bitterly."
Nearby, Confederate Gen. Robert E. Lee was preparing to renew the fight. He told his officers, "We will attack in the morning as early as possible."