Members of an elite corps of Civil War historians who take visitors on in-depth tours of the Gettysburg battlefield claim new rules being imposed by the National Park Service will threaten their nearly century-old organization.

The park service, as part of its reorganization ahead of the opening of the battlefield's new visitor center in April, established a new tour schedule and reservation system and changed how and when the licensed battlefield guides get paid.

The Association of Licensed Battlefield Guides says the new system effectively ends their ability to control their work schedules and will reduce the number of tours they give. It may also reduce their tips.

"I am fearful that this will destroy the guiding the way it has existed since 1915," said Robert Hohmann, president of the association, which represents 125 of the 155 licensed guides. "I think the guides will see a loss in income and that could force some out of guiding."

The epic three-day clash at Gettysburg, July 1-3, 1863, involved 165,000 troops and was perhaps the pivotal battle of the Civil War. The rolling fields and stands of trees, 6,000 acres in total, may be the most visited Civil War battlefield in the nation.

Until now the guides, many of whom are retirees, were paid in cash ($45 a carload and up to $135 per bus) following the tour. About 20 percent of a guide's total income is generated in tips on top of the fee for their high-level, two-hour historical overviews of the 1863 battle.

The park service says the new system to schedule and pay for tours in advance will better accommodate the 1.7 million people who visit the battlefield each year.

"We're trying to improve visitor services," said Katie Lawhon, a park spokeswoman. "Right now, a family comes to Gettysburg and has no assurance they can get a licensed guide and they have to wait in line."

She said that with online reservations and computerized schedules, visitors will be able to plan in advance and be guaranteed a tour when they arrive. Paychecks will be issued bimonthly to guides.

"As a self-employed contractor they are not only setting rates but they're holding my pay for two weeks and then telling me when I must come to work," said Mike Strong of York, a member of the association's executive committee and full-time guide since 1994.

Guides are concerned that with payments made in advance, they will no longer receive tips after the tours.

Other guides, though, contend the new system will make their work easier, and describe the dispute as a small disagreement that has been blown out of proportion.

"It makes me more efficient and I can prepare better," said guide Joanne Lewis, of Hagerstown, Md. She said she does not think the payment plan is detrimental, "as long as we are paid and paid fairly."

The licensed battlefield guide organization, generally recognized as the oldest professional guide service in the nation, has a rich history. It was formed by Congress at the request of Civil War veterans who, seeing a proliferation of freelance tours of varying quality, wanted to ensure the story of the battle was told accurately to future generations. Guide candidates must complete a rigorous testing process including written and oral exams. There have been only 500 licensed battlefield guides since the program's inception.

The guides, who pay an annual $360 license fee, escort about 290,000 park visitors each year generating a total of $1.5 million in income, said Hohmann.

Hohmann, a retired teacher who moved from Pittsburgh to Gettysburg to fulfill his dream of becoming a guide, said he conducts between 370 and 400 tours a year. He said he earns about $30,000 that helps supplement his pension and investment income. Others, though, he said, rely solely on the tour fees for their income.

Strong, a former quality-control supervisor at Caterpillar, said battlefield guiding is the ideal retirement job. "It's my passion, like getting paid for playing golf." But he said if the new system becomes too onerous he'll find something else to do.

"I'm not going to do something that aggravates me," he said. "I'll go usher at the ballpark."

Contact staff writer Amy Worden at 717-783-2584 or aworden@phillynews.com.