Brian Willson, who lost his legs trying to block a munitions train in a protest against U.S. policy in Central America, will return to the tracks Thursday to mark the first anniversary of his maiming, protest organizers said Tuesday.

Jay Hendrick of Nuremberg Actions, which coordinates the year-old, 24-hour vigil outside the gates of the Concord Naval Weapons Station, said Willson would attend a Thursday morning ecumenical service as well as a Saturday demonstration that organizers hope will attract 10,000 people.The theme of service is the "resilience of the human spirit," Hendrick said.

"Brian (Willson) will be there, and the last I heard (actor) Martin Sheen is going to be there as well," Hendrick said.

No acts of civil disobediance were scheduled, Hendrick said, "but if a munitions truck comes out during the service, there may be some arrests."

Nuremberg Actions began coordinating frequent demonstrations at the weapons center 40 miles east of San Francisco last July. The group says munitions that leave Concord on trains and trucks for Port Chicago, a short distance away, are shipped to the Contra rebels fighting Nicaragua's Sandinista government.

On Sept. 1, 1987, Willson, 47, a Vietnam veteran, was struck by a train as he and others tried to block the tracks. He lost both legs and subsequently became the symbol of the movement.