SHANKSVILLE —The 40 passengers and crew aboard Flight 93 became worthy successors to the heroes of U.S. battles dating back to the Revolutionary War when they made the decision to fight the terrorists who hijacked their plane, former Secretary of State Colin Powell said Friday.

Speaking under a dull gray sky in a field near Shanksville to mark the eighth anniversary of the Sept. 11, 2001, attacks, Powell said the choice was clear for the passengers and crew of the plane taken over by four suicidal fanatics.

"The choice before them was clear and daunting: If they had any chance of survival, they had to attack not only to save themselves, but to save hundreds, if not thousands, of their fellow citizens and to show the terrorists that they would never defeat us," Powell said. "They refused to let it just happen, they acted."

The terrorists pushed them to the back of the plane, thinking that would keep them under control, he said: "But they misunderstood Americans. We fight back. We will never be cowed.

Flight 93 was traveling from Newark, N.J., to San Francisco when hijackers took it over with the likely goal of crashing it into the White House or Capitol. The 9/11 Commission concluded the hijackers downed the plane in Pennsylvania as the hostages revolted.

Retired Gen. Tommy Franks said the memorial would remind future generations of the character revealed through the adversity faced by the passengers and crew.

"Their lives were not taken, their lives were given," Franks said.

Several hundred people attended the morning ceremony, but visitors continued to arrive through the morning and into the afternoon.