CAPE CANAVERAL, Fla. (AP) _ Over 100 protesters, including Dr. Benjamin Spock, were arrested Saturday when they scrambled over a fence at Cape Canaveral Air Force Station as thousands of peace activists protested the launch of a Trident 2 missile.

Spock, 83, brought a cheer from many in the crowd of at least 4,000 as he hoisted himself over the fence and dropped to the ground. Dozens of other protesters jumped the fence and others went around it.

Spock and his wife, Mary Morgan, were among 128 protesters arrested and charged with misdemeanor counts of trespassing, said Sgt. Mike Beeman, a spokesman for the air base. He said a figure of 138 given earlier by the sheriff's department was incorrect.

Those arrested were bused to the Brevard County Jail, where they were held under canopies set up in the jail yard.

''It's a good cause, a very good cause,'' Spock said, peering from a window in the prisoners' bus.

The demonstrators marched on the air station to protest nuclear proliferation and the test launch Thursday of the Trident 2.

In related protests, about 100 people demonstrated outside a Navy radio facility in Clam Lake, Wis., and about 50 people gathered in front of the Knolls Atomic Power Laboratory in Niskayuna, N.Y., where a submarine nuclear propulsion system was developed.

Eight people were arrested on trespassing charges when they walked through a gate at the Wisconsin facility, the site of an ELF, or extremely low frequency, radio transmitter that sends coded signals to submarines at sea.

''Cape Canaveral means something special to the American people so it's good to be making our protest here,'' Spock said of the home of America's space program. ''They'll immediately understand the connection here.'' The peace marchers gathered at the entrance of Port Canaveral to make the three- mile march to the gate of the Air Force Station and participate in civil disobedience.

The protesters voicing their concern over the nuclear arms race ranged from high school students to peace movement activists to wealthy retirees. Organizers and police placed the crowd at approximately 4,000.

''I'd like to see my grandchildren grow up and for their children not to have to face this stuff,'' said Bert Blankenship, 63, wearing a straw hat with a hatband that said ''I'm a grandma for peace.''

About 125 counter-demonstrators had tried to stand in the way of the activists, but were outnumbered. No violent was reported.

''Hundreds of people called me and told me tey felt the same way and they would come out here and show the world how we felt,'' said David Kraak, a counter-protester calling for ''peace through strength.''

An Amtrak train that rally organizers dubbed the ''Peace Train'' brought more than 100 protesters to the rally. Buses brought hundreds of others wanting to join the march.

''For 20 years, I've been watching Benjamin Spock and Jane Fonda speak against our national defense and values. I'm getting sick of it,'' said Joel Ruth, 34, of nearby Indialantic, one of the organizers of the counter protest. ''These people have no real popular backing. We hope this will be their Waterloo.''

About 200 protesters ended a month-long, 217-mile peace march Friday that started in St. Marys, Ga., where Trident submarines will be based. The Trident 2 missile would be carried on the submarines and carry multiple warheads.

By Friday, the number of people arrested from the vanguard of the protest, including those who tried to halt a Thursday test launch of a Trident 2 missile, had swelled to at least 66.

''The fact that the launch went off successfully makes the rally particularly appropriate,'' Spock, 83, told activists Friday. ''The question is not the success of the launch, but the future of our world.''

Protesters arrested earlier in the week faced an unsympathetic judge in Brevard County Court.

''I hope you'll take your protest to Soviet Russia after you're finished in Florida,'' Judge Peter Haddad told protesters Friday. ''You've got the whole jail in an uproar. You've got police officers working double time. You're humiliating the military.''

Most of the people arrested on trespassing charges have been detained because they refuse to identify themselves.

Authorities erected four large canopies in the yard of the Brevard County jail to accommodate up to 200 protesters.

The 237 jail beds in Titusville are full, and about 100 more inmates, including 42 protesters, were sleeping on mattresses on the floor, said Brevard Sheriff's spokeswoman Joan Heller.