GETTYSBURG, Pa. — After surviving one of the American Civil War’s pivotal battles 150 years ago, the Pennsylvania borough of Gettysburg once again faces invasion.
The community about 125 miles west of Philadelphia is readying for as many as 4 million visitors during its commemoration of the clash between Union and Confederate forces in July 1863, and the landmark presidential speech in November of that year as the war raged.
‘‘In 1863, we had more than 165,000 uninvited guests come to town. At least this time around, we got the chance to plan,’’ Randy Phiel, a commissioner of surrounding Adams County, said in an interview. ‘‘This is our Olympic moment.’’
The anniversary of the war’s bloodiest battle, coupled with the Oscar-winning 2012 movie ‘‘Lincoln,’’ will bring Piotr Narloch and five pals from Krakow, Poland, to help reenact part of the fighting. The commemoration has tour operators and travel sites touting the borough of about 7,600 residents as one of this year’s top destinations, according to Carl Whitehill, a spokesman for the Gettysburg Convention and Visitors Bureau.
‘‘We’ve been planning for this anniversary for several years and we’re hoping things go smoothly,’’ Whitehill said. ‘‘But 4 million is a pretty substantial number for a town of our size.’’
The estimated 15,000 Civil War reenactors on hand this year, while smaller in number compared with the millions of tourists, will stand out with their rifles, pitched tents, and campfires on farms near the battlefields. They’ll include Narloch and his Polish friends.
The group will travel 5,000 miles to stage the July 2 Culp’s Hill assault by the 14th Louisiana Infantry Regiment, a Confederate unit largely composed of Polish immigrants. They’ll join other history buffs at the Bushey Farm outside Gettysburg starting June 27.
‘‘It will be my great honor’’ to represent those who tangled with Union soldiers in the July heat, Narloch said by e-mail. ‘‘We can’t wait to see the thousands of reenactors, hundreds of horses and cannons at Gettysburg.’’
The epic battle began as Confederate forces under General Robert E. Lee invaded Pennsylvania during the war’s third year. Lee’s Army of Northern Virginia was beaten back by the Union’s Army of the Potomac led by General George G. Meade, a Pennsylvanian. Meade defeated a desperate charge by General George Pickett’s men on the last of three days of fighting, which left more than 50,000 combatants dead, wounded or missing.
One reenactment will use almost 70 cannons, according to Thomas Alexander, a retired Maryland police officer who leads the Confederate artillery for reenactments planned on two farms north of Gettysburg. To prepare, Alexander said he has studied the terrain to position the guns for engagements such as the Union advance into the Wheat Field and the Confederate flanking move at Little Round Top, both on the battle’s second day.
‘‘We’re trying to make sure it represents, as closely as possible, what took place while giving spectators a chance to safely see the action,’’ said Alexander, a member of the Second Maryland ‘‘Baltimore Light’’ Artillery. ‘‘It takes a lot of time and planning to get it right.’’
Assembling a historically accurate uniform and gear, including a rifle, can cost as much as $2,500, said William Coe, whose namesake ancestor was among Gettysburg’s casualties.
Reenactments provide living history, said Coe, who portrays Sergeant William W. Coe in the 21st North Carolina Infantry. Coe, 53, said he moved near Gettysburg from Cinnaminson, N.J., in December 2011, to be close to where his namesake was wounded in the charge up Cemetery Hill.
The men in the re-created units come from across the country and 16 nations, including Britain, France, Sweden, and Romania.
David T. O’Daniel, a member of the 69th Pennsylvania ‘‘Irish’’ Volunteer Infantry Regiment, will be growing out his gray beard and dyeing it red so he can more accurately resemble Color Sergeant David Kinairy, who carried one of the unit’s green battle flags during the third day of combat.
‘‘I’ll be going to Gettysburg to fight the rebels and stack them like cord wood, because that’s what we do,’’ O’Daniel said in an interview. ‘‘We’re the Irish,’’ he said, displaying a green-and-blue tattoo with the unit’s crest.
O’Daniel is a descendant of Cyrus O’Daniel, a corporal in the regiment known as the ‘‘Rock of Erin.’’