Battlefield "staff rides" originated in 1870, when Gen. William T. Sherman used them as a way to go over what had happened during an engagement, to try to get inside the minds of the field commanders and to learn lessons that could be applied later. And until the battle of Normandy, in 1944, Gettysburg was the most studied battle for such staff rides.

It's still one of the most scrutinized battles, and military officers from around the world walk the Pennsylvania fields and ridges where 172,000 Union and Confederate troops clashed in three bloody and decisive days of fighting in July 1863.

For Hopkins, the staff ride of Gettysburg has become an annual feature of a course in the Police Executive Leadership Program, one that attempts to give police commanders a sense of what happened there--what went right, what went wrong--and why. It's a daylong attempt to reach back 135 years for lessons that can be applied to modern leadership and the complexities of contemporary organizations.

"All the lessons of leadership are there," said Sheldon Greenberg, a former police officer who directs the PELP program in the School of Continuing Studies, now in its fifth year. "You had bosses not listening to subordinates. You had commanders who were not in charge of some troops who said, 'I know you're not under my command, but I need you to do this.' You had commanders who thought, for the good of the corps, I'll just move over here, and they left huge gaps in the line."

On a recent afternoon, 25 second-year students in the PELP program-- all working police officers--surveyed the battle of Gettysburg from the early shots fired on McPherson's Ridge to the bloody assaults on Little Round Top and Culp's Hill to the desperate, gallant assault of Pickett's charge.

The staff ride was put together by Patrick A. Martinelli, a senior faculty associate in the School of Continuing Studies and an instructor in the PELP program, and led by Gary Kross, a licensed battlefield guide.

Before embarking on the staff ride, Martinelli had gone over the events leading up to Gettysburg, how General Lee's Army of Northern Virginia of 75,000 men had marched into Maryland and Pennsylvania, aiming for Harrisburg, where they planned to cut off rail and communications links to Washington.

Gen. George Meade, appointed just three days before the battle of Gettysburg to head the Army of the Potomac's 95,000 men, had been sent from Washington by President Abraham Lincoln to head off the Confederates and protect the capital.

Both armies were converging on Gettysburg on July 1, when fighting broke out to the north of town on an incline called McPherson's Ridge. A Union Cavalry officer, Gen. John Buford, with only 2,800 men compared to 6,500 Confederates advancing from the north, acted decisively to stall the Confederates.

Buford, seeking to protect high ground south of Gettysburg, ordered his troops to fire their rifles and cannon in such a way as to trick the Confederates, at least initially, into thinking they were facing a much stronger infantry force.

The ruse worked well enough to stall the Confederates until Union infantry could arrive from the south, and while the Union sustained heavy losses on the first day, and were driven back through the streets of Gettysburg, ultimately they got possession of the good ground.

"It's a good example of positioning," Martinelli said. Even though Buford knew he couldn't win that initial battle, he had a defensive plan with the ultimate goal of protecting the good ground, which the Union held and ultimately used to win the battle of Gettysburg.

"It's a sacrificial stand to buy time," Kross said. Buford "is really the unsung hero of the battle of Gettysburg."

On the second day, the Union had entrenched itself along the 3-mile-long defensive position. One general, not happy with having to defend the lowest point in the Union line, moved his troops forward without consulting anyone, leaving a huge gap in the Union left. Decisive action by another general and a creative bayonet charge by a Maine college professor saved the Union left--both examples of creative right-brain thinking, Martinelli said.

The Union right was saved by steady, stubborn preparations made by the oldest soldier on the field, Gen. George Green, 63, an Army engineer who had his 1,500 men work throughout the day building fortifications to protect Culp's Hill, even when it looked as if they would not be attacked.

"This was an example of a Union victory because General Green prepared even though it appeared not to be necessary," Kross said.

Martinelli told his students that the left-brain thinking of General Green and the right-brain thinking of Colonel Chamberlain helped win the day for the Union. He used it as an example of a good metaphor for why, as managers, they need to be "whole brained" in their approaches to solving problems and managing employees.

Tactics and technology also played a role at Gettysburg. General Lee, adhering to ideas of war dating to the early 19th century, declined advice by Gen. James Longstreet to go around the Union troops and let them attack his forces. Instead, on the third day of battle, he sent 15,000 of his soldiers across a mile-wide stretch of open field under heavy cannon and rifle fire to try and break the Union line.

But the cannon and rifles used in the Civil War could shoot farther and more accurately, and Lee's troops were devastated. Technology of the arms used in battle had made such tactics obsolete.

So good leadership and strategy have to involve responding to technological change, Martinelli said.

Of course, General Lee's plan could have worked, especially if he had the Union forces outnumbered, as he thought he did, Kross said. But two corps of Union soldiers had marched from as far as 30 miles away to support the Union lines.

Bill O'Toole, a Montgomery County police officer in the course, said he clearly saw that much of what the leaders at Gettysburg faced, modern police commanders face. One lesson: "Things never go according to plan. You have to be prepared to react and evolve."

Jim Vandegrift, a lieutenant in the Maryland state police said he had been to Gettysburg numerous times over the years and had often sat at different parts of the battlefield trying to envision how things happened. He even took a staff ride as a member of the National Guard.

Jim Vandegrift, a student in SCS's Police Executive Leadership Program, on the job.

But he had never heard the information on Buford and Green so clearly explained, and he said he learned a lot about what happened there and how things apply to the business world. For instance, he said he understood more why, when General Lee refused his advice to go around the Union troops and let them attack, Longstreet went along with Lee's decision without complaint.

"You have the same thing in the police and in business," Vandegrift said. "You may disagree with a strategy or a decision, but once the decision is made, you need to get behind it and support it."