The trap was set.

The bait - a small unit of mounted Union troopers - peppered away at gray-clad cavalry east of Gettysburg, as if poking a hornet's nest, then hurriedly galloped off.

In hot pursuit, the Confederates rode into the jaws of a large Federal force - and a maelstrom of muzzle flashes, gun smoke, thundering hooves, and whinnying horses.

That clash Friday gave thousands of spectators a taste of what war was like 150 years ago, when the young, fair-haired Gen. George Armstrong Custer lured Southerners into an ambush on July 2, 1863, on the road to Hunterstown.

The restaged fight outside Gettysburg was one of two that included another ferocious battle known today simply as the "Wheatfield," where Union forces were cut to pieces and fought hand-to-hand with Confederates.

Many spectators cheered on the troops as the tide of battle shifted back and forth and stood amazed at the jarring sound of cannon volleys, and spectacle of massed cavalry and large marching armies with shouldered muskets.

"It looks like I imagined it would, but now I'm seeing it," said Mark Kraschneske, 49, of Erie, as he trained his video camera on the cavalry's flashing swords. "I've never been to a reenactment, but I think this is important to do.

"You have to know where you've been in history so you know where you're going," he said.

Nearby, Wayne Yoder, who is Amish, watched the battle with his wife and 4-year-old son. They had a friend drive them 500 miles from Rome City, Ind., to see the reenactment.

"In an actual war, it would be a lot more intense," said Yoder, 33, an RV factory worker. "But this gives you a feel for how it would be."

Steve Alexander was resplendent in a black velvet uniform, a dashing figure out of a romance novel. He strapped on his sword, adjusted his handgun holster, then put the bridle on his horse and mounted it.

The image was complete. Alexander was Gen. George Armstrong Custer, right down to the curly golden locks of hair.

"This is the way he would have looked," said Alexander, who has written two books on Custer and lives in the house where the general lived with his wife in Monroe, Mich. "When he showed up at Gettysburg, everybody thought he was a dandy, but when he led troopers in battle, they changed their minds."

Nearby, Custer's men were getting ready for the fight, too. They would be sent out to stop Confederate cavalry, which, in 1863, was moving to support Southern infantry at Culp's Hill.

Zachary Hubert and Todd Kidd cleaned their carbines in their tent, which was filled with saddles, bridles, swords, and handguns.

"We're just firing blanks, but you have to be careful," said Hubert, 24, a trauma surgery nurse who lives in Lancaster. "In closer engagements, you point your guns up in the air."

Reenactors often feel a chill running up their spines - what they call "magic moments" - during the battle when 2013 fades away, leaving 1863, with all the sights, sounds, and smells of the war.

"When you see a flood of gray coming toward you, you get a sense of it, the power and emotion," Hubert said.

The battle re-creations are "exciting and fun because there are no bullets in the guns and nobody is really trying to hit you with a sword," said Kidd, 23, a Penn State senior who lives in Lancaster.

Sometimes, the action gets a little too real. "People can get cut with sabers and get black powder burns from muzzle flashes," he said.

During Friday's 11 a.m. cavalry battle, Alexander rode onto the field and crossed swords with the enemy - to the cheers of a crowd of about 13,000. Up to 25,000 each day on Saturday and Sunday will bring the total number of spectators to about 70,000 over the four-day event, organizers said Friday. About 12,000 reenactors have participated.

In the 1863 clash, Custer's horse was shot out from under him and a Confederate trooper was about to slash him with a saber when Union Pvt. Norvell Churchill deflected the blow, rescued the general, and shot the enemy. "If I was Custer," he said, "I'd be happy to be alive."

July 2, 1863, was bright and sultry as Confederate Gen. Robert E. Lee and his commanders gathered on Seminary Ridge to plan the army's next move.

Lee's "old war horse," Lt. Gen. James Longstreet, wanted to wait for more troops to arrive before renewing the attack. He sat on a log whittling a stick awaiting Lee's decision.

"I never like to go into battle with one boot off," Longstreet told another officer. Lee's mind was made up, however. "It was determined to make the principal attack on the enemy's left," Lee reported. Other troops would threaten the center of the Union line and the right flank.

At 10 a.m. he told Longstreet, "I think you'd better move on." Longstreet spent the next several hours maneuvering his command to avoid enemy detection.

The assault did not begin until about 4:30 p.m. and when it did, it ran into an unexpected problem: The Union III Corps commanded by Gen. Daniels E. Sickles, thousands of battle-hardened veterans who had marched forward from the federal line on Cemetery Ridge about three-quarters of a mile.

Battles in the wheat field and a peach orchard left the ground covered with dead and wounded. Union Gen. Sickles was down with a shattered leg and his III Corps was nearly destroyed.

Union Col. Regis de Trobriand recalled: "It was a hard fight. The Confederates appeared to have the devil in them."

Union Pvt. John W. Haley wrote in his journal: "Blood poured out like water. Both sides understood the value of this position."

For many reenactors, the Civil War hobby is in their blood. They have ancestors who fought in the war and they've had an endless fascination with it over decades.

"I had an ancestor in the 59th North Carolina" regiment, said Dwight Bass, 62, of Wilson, N.C., as he sat outside a tent in the Confederate camp. "I also remember my dad being into the war.

"He bought an original Springfield musket for $15 in 1956," said the painting contractor. "He and others would shoot black powder weapons."

Later on, Bass recalled the excitement of the Civil War centennial and began reenacting in 1979, sometimes portraying a quartermaster and other times, an infantry soldier.

As the Union and Confederate reenactors clashed this week, he channeled a Southern soldier of 1863: "This is our chance to show them we're as good as any army in the world and to show them up North."