Succeeding on his third try to visit them, President Bush comforted thousands of Boy Scouts (search) on Sunday at a national jamboree marred by the electrocutions of four leaders and stifling heat that sickened 300.

"The men you lost were models of good citizenship," Bush told the estimated 50,000 Scouts, leaders and visitors attending the event near Bowling Green (search), Va., where boys yelled "Boy Scouts Rock!"

"As scout leaders, they devoted themselves to helping young men develop the character and skills they need to realize their dreams. These men will always be remembered for their leadership and kindness, and you scouts honor them by living up to the ideals of the Scouting they served."

Marine One landed in a grassy field and Bush, a former Cub Scout in Texas, was ferried by van to a stage where he was met by a sea of cheering Scouts wearing fatigue green uniforms covered with colorful patches and badges.

As the sun set, Bush told the crowd that the first man he often sees every morning, chief of staff Andy Card, is a former Scout from Massachusetts; Vice President Dick Cheney (search) was a Boy Scout in Wyoming; and Defense Secretary Donald Rumsfeld was an Eagle Scout in Illinois.

Bush's speech was about patriotism and community and military service to the nation, but he also recalled how his mother, former first lady Barbara Bush, was the den mother of his Scouting troop. "It's about the time her hair turned white," he joked.

Before Bush arrived on stage, an Army band performed and a man wearing an Army T-shirt led groups of Scouts in chants of "OO-rah" and "U.S.A." Tall pines provided a backdrop for blue, red and black hot air balloons emblazoned with military and Scouting emblems.

It was Bush's third attempt to travel to Fort A.P. Hill, the Army base hosting the Jamboree where Scouts are trying to end their 10-day gathering with cheery memories of mountain biking, fishing, scuba diving and trading patches with newfound Scouting friends across the nation.

On Wednesday, scouting enthusiasts waited hours in the heat for Bush, who later canceled his appearance because of threatening storms. Scouts began collapsing from high humidity and temperatures in the high 90s. More than 300 people were treated for heat-related illnesses.

Bush's second attempt to visit the Jamboree was postponed from Thursday at the Scouts' request. Officials wanted to review safety procedures for large crowds and replenish water and other supplies.

The illnesses came as the Jamboree participants were still trying to overcome the deaths on Monday of four adult Scout leaders who were electrocuted in front of several Scouts when a metal pole at the center of a large dining tent touched power lines. The tent caught fire and the men burned. An investigation into the accident is under way.

The day before, a volunteer was taken to a hospital where he died of an apparent heart attack.

"I appreciate the rain check," Bush said.

The weather was considerably cooler Sunday, but Scout officials took extra precautions. Scouts hiking to the arena from the most distant subcamp about seven miles away set out at 3:45 — more than an hour later than Wednesday — to give them less waiting time in the sun.

Several running buses with signs on the windshields reading "Cooling Station" were available, there were more tents to provide shade and stretchers were spaced out over the field in case they were needed.

Cases of bottled water dotted the sloping lawn of the arena like hay bales.

Even so, the day was not without minor incident.

A military helicopter carrying several photographers made an emergency landing at the Jamboree after its engine failed Sunday afternoon, said Jamboree spokeswoman Renee Fairrer.

She said the Blackhawk helicopter was carrying adult photographers for the Boy Scouts. She was unable to say how many people were on the helicopter, which she said landed at its designated spot on base.