avid Reed likes to go to Monocacy National Battlefield near Frederick from time to time, but he's no ordinary visitor. During his most recent visit, the Northwest Washington resident got a private tour of the newly restored porch on the Worthington House, a large farmhouse built in 1851 that's an important part of the battlefield park. Reed, a retired association executive, has a personal interest in the historic significance and preservation of the Worthington farm: It once belonged to his great-grandfather.

John T. Worthington, a prominent Frederick farmer who bought the 300-acre farm in 1862, couldn't have known that his orchards and wheat fields would become a killing ground two years later during the Battle of Monocacy, a little-known but key Civil War conflict that was fought 140 years ago Friday. The Worthington family took cover in their cellar as Confederate troops attacked the Union line between their farm and the nearby Thomas farm. Reed's grandfather, Glenn, who was 6 years old at the time, spent the day peeking out from behind boarded-up windows to watch the fighting. At one point, Rebel soldiers moved an artillery piece onto their property, and every time it was fired, one of the Worthingtons' roosters would crow loudly. All nine of the family's horses were taken by the Confederate invaders.

Reed remembers his grandfather as "a tall man with a stately gait." Glenn Worthington became a lawyer who was later appointed chief judge of the Sixth Judicial Circuit of Maryland, but the little boy who witnessed a Civil War battle from his cellar window never forgot that experience. Worthington wrote the first major book on the Battle of Monocacy and was instrumental in getting Congress to create a national military park at the battlefield, which it finally did in 1934 -- the same year he died.

"I'm the last surviving grandchild [of Glenn Worthington]," says Reed, who hopes to be on hand this weekend for some of the activities surrounding the commemoration of the battle's anniversary. Through living history programs, infantry demonstrations, cannon firings and more, visitors to the national battlefield will learn why the war's only major Confederate victory on northern soil will always be remembered as the "battle that saved Washington."

July 1864 was the fourth summer of the Civil War, and the nation was weary of the bloodshed. President Abraham Lincoln's prospects for reelection in the fall did not look good. The two primary opposing armies -- Gen. Ulysses S. Grant's Army of the Potomac and Gen. Robert E. Lee's outnumbered Army of Northern Virginia -- were entrenched at Petersburg, Va., just 25 miles south of the Confederate capital at Richmond. Many of the Union troops at Petersburg had been sent there from Washington, leaving the northern capital nearly defenseless.

Lee devised a plan that he hoped would force Grant to divert troops from Petersburg. He ordered Lt. Gen. Jubal Early to take a small army of about 15,000 men, clear the Shenandoah Valley of Union troops, then invade Maryland and assault Washington from the north. If at all feasible, Early's mission was to capture, or at least threaten, the nearly undefended federal capital and deal the Union an incapacitating blow.

Lee also tasked Early with another scheme while on his northern raid: If possible, capture Point Lookout in Southern Maryland and release many thousands of Rebel soldiers being held prisoner there. The Confederate commander desperately needed more men to bolster his dwindling army.

"Old Jube," a rough-talking, tobacco-chewing West Point graduate who had served in the Virginia legislature before the war, left the Richmond area with his men on June 13 and proceeded to the Shenandoah Valley. After days of grueling marches of up to 24 miles a day in the scorching heat, the Confederates arrived in the Harpers Ferry area on July 4 and celebrated Independence Day by plundering federal supplies. On July 5, Early's army forded the Potomac River and invaded Maryland -- the third and final time the Rebels would bring the war onto northern soil.

By the evening of July 8, the Confederates had arrived on the outskirts of Frederick, within striking distance of Washington via Georgetown Pike (now Route 355). Among them were a former vice president of the United States now fighting for the South (John C. Breckinridge), a future U.S. senator and governor of Georgia (John Gordon), and tough military men like Major Gens. Robert Rodes and Stephen Ramseur, neither of whom would survive the war. Far from its supply lines, this veteran army was poised to advance the next day toward Washington, hoping to alter the course of the Civil War.

What the invaders didn't know was that a Union general in Baltimore had taken it upon himself to place all his available forces in the path of the Rebel army and was lying in wait for them along the east bank of the Monocacy River just south of Frederick.

On July 9, 140 years ago, the Battle of Monocacy exploded on the farms of the peaceful river valley, as Early's men met fierce resistance from the 5,800 Union forces of Gen. Lew Wallace -- nearly half of them inexperienced home guards and 100-days men (temporary soldiers). His men held out until about 4:30 p.m., when, after seeing the fourth Confederate battle line of the day form, Wallace ordered his tired and outnumbered troops to retreat. Wallace -- who after the Civil War would achieve greater fame as the author of the book "Ben Hur" -- was satisfied that his little army had done all it could to stall the Rebel advance on Washington by one full day, enough time to ultimately doom the Confederate mission.

By the time Early's battered men reached Fort Stevens on Washington's northern perimeter on the afternoon of July 11, the Confederates were in no condition to launch an attack on the still lightly defended capital. They had lost 900 men at Monocacy, and "of those remaining," Early wrote later in his memoirs, "a very large number were greatly exhausted by the last two days' marching, some having fallen by sunstroke, and I was satisfied, when we arrived in front of the fortifications, that not more than one-third of my force could have been carried into action."

On July 12, the Battle of Fort Stevens took place, such as it was; but by then, veteran Union soldiers from the 6th Corps had reached the fort and its environs and were positioned in defense of the city. Fierce but brief fighting occurred in the sweltering afternoon heat as the soldiers in blue clashed against their foes in gray, and by nightfall the Rebels were in retreat toward the safer haven of Virginia.

It was the only time during the Civil War that a Confederate army was literally at the gates of Washington, giving all those within -- residents, lawmakers and the military hierarchy alike -- a terrible scare.

The plan to free the Confederate soldiers at Point Lookout was also called off, but Old Jube was apparently not unhappy with the performance of his army. At a meeting with his staff on the night of July 12, he said to an officer, "Major, we haven't taken Washington, but we scared Abe Lincoln like hell!"

Today, Monocacy National Battlefield is a pastoral 1,600-acre tract of rolling green fields and dairy farms just south of Frederick's Francis Scott Key Mall and sprawling commercial development.

"For a long time, people didn't know about the park or the battle," says Cathy Beeler, Monocacy's chief of resource education and visitor services, adding that the national battlefield "has lots of historic structures."

In addition to the Worthington farm, the Thomas and Best farms also date back to the battle (as does Gambrill Mill, which houses the Visitor Center) and saw considerable action; the Thomas farm in particular was the scene of intense fighting during the day-long conflict.

The historic Best farm -- now just a stone's throw from an office park and a strip of superstores -- has an intriguing past that predates the Civil War: It was recently found to be the site of what may be one of Maryland's largest slave villages. Archaeologists have found buried remnants, dating to about 1800, that indicate a cluster of crude dwellings. At the time, the property was a plantation that belonged to the Vincendieres, a French-West Indian family who owned 90 slaves.

The Best farm is also notorious among Civil War buffs as the place where, in early September 1862, Union soldiers found -- wrapped around three cigars -- the famous "Lost Orders No. 191" in a field that had been recently occupied by Confederate troops. The papers contained Gen. Robert E. Lee's plans for troop movements for his first advance into northern territory, and should have been the key to an imminent Union victory. Instead, Union commander George B. McClellan did not use the orders to his advantage, and the ensuing Battle of Antietam -- the bloodiest single day in U.S. history -- was a tactical draw.

Several roadside plaques at the edge of the Best farm on Route 355 describe the lost orders, the role of the Best farm and Early's raid. A monument at the same location commemorates the Southern soldiers who fell at Monocacy, and another honors the Maryland soldiers from both sides who lost their lives there. Three additional monuments -- for New Jersey, Pennsylvania and Vermont troops who fought valiantly at Monocacy -- can be visited on the driving tour of the battlefield.

The battlefield park is bisected by Interstate 270 and Route 355. Some of the heaviest fighting of Monocacy was right where many thousands of cars whiz by every day on a straight stretch of I-270, between the Worthington and Thomas farms. Beeler is worried about the impact that any future widening of I-270 would have on both battlefield properties. "It's a real problem," she says.

Monocacy National Battlefield offers several pleasant hikes that depart from the Worthington House. The 1.9-mile Brooks Hill loop, which winds through woodland areas and farm fields, boasts a great view of the former battlefield area from the top of -- you guessed it -- Brooks Hill, a gradual climb that shouldn't daunt even the most reluctant hiker. The 1.6-mile Worthington-McKinney Ford loop takes you down and along the Monocacy River to the ford where Maj. Gen. John Gordon's infantry and Brig. Gen. John McCausland's cavalry crossed the river -- under fire from Union troops -- during the battle. There's also an easy half-mile loop trail to the river near the Gambrill Mill Visitor Center.

The battlefield park will host special programs this weekend, but throughout the year the Visitor Center (soon to be replaced with a bigger facility with new exhibits) features an electric map orientation program of the battle (kids especially like watching the lights and hearing the battle sounds), interpretive exhibits and an interactive computer program. The self-guided auto tour is four miles round-trip, and is helpful in understanding the scope and terrain of the battle, as well as for seeing the monuments. You can pick up trail and driving tour maps at the Visitor Center.

David Reed says he remembers his grandfather and other members of his family telling stories about the Battle of Monocacy. This weekend, if you reverse the movement of Jubal Early's Washington-bound troops and instead head north to the Frederick County battlefield, make sure you visit the imposing Worthington House with its stunning views of the surrounding farmland -- and imagine little 6-year-old Glenn Worthington peeking out from one of the cellar windows, witnessing history in the making.

ANNIVERSARY EVENTS -- Monocacy National Battlefield, 4801 Urbana Pike, about three miles south of downtown Frederick on Route 355. 301-662-3515. www.nps.gov/mono/home.htm. From Washington, take Interstate 270 to Exit 26 (Urbana). Turn left onto Route 80 and proceed two-tenths of a mile to stop sign. Turn left onto Route 355 north. The Gambrill Mill Visitor Center is 3.7 miles north on Route 355. On Saturday and Sunday, costumed interpreters near the Gambrill Mill Visitor Center will provide living history programs from 11 to 3, while volunteers will greet visitors on the newly restored porch of the Worthington House to share other events related to the Battle of Monocacy. Cannon firing demonstrations will take place at 11, 1 and 3, and there will be infantry demonstrations at noon and 2. At 12:30 and 2:30, a program featuring reenactment of the 87th Pennsylvania (one of the regiments that played a key role during the battle) will be an interactive opportunity to learn about various tactics, technology and troops involved in the conflict. Everything is free, and the park is open from 8:30 to 5 daily.

Patricia Weil Coates writes frequently about travel and recreation. Based in historic Frederick, she is an avid Civil War buff.

David Reed in front of the Worthington House at the Monocacy National Battlefield. Reed's grandfather, Glenn Worthington, witnessed the 1864 Battle of Monocacy from his cellar window. Cathy Beeler is chief of resource education and visitor services at the 1,600-acre park, which includes open fields and farms.