SAN FRANCISCO -- Demonstrators marched through downtown Wednesday holding signs, chanting anti-war slogans and handing out "unhappy birthday" cake as part of a day of nationwide protests to mark the fifth anniversary of the U.S. invasion of Iraq.

Nearly 150 protesters had been arrested by late afternoon for blocking traffic and chaining themselves to buildings, police said.

The rallies, which drew hundreds to the city's busy financial district, were mostly peaceful, though some demonstrators threw glass Christmas ornaments filled with paint at police, said Sgt. Steve Mannina, a San Francisco police spokesman.

Black balloons were tied to trees along the city's main downtown thoroughfare, and protesters at a table offered coffee and oranges and a cake reading "Unhappy 5th Birthday -- Stop the War Now" to passers-by.

Daniel Ellsburg and other Vietnam era protest veterans joined hundreds of demonstrators in the streets of San Francisco Wednesday.

Ellsburg, famed for the release of the Pentagon Papers, was among a group of protesters lying down on San Francisco's busy Market Street. Many were arrested at the intersection -- some in confrontations with baton-welding police officers.

"These protests have been going on for a long time I'm sorry to say," Ellsburg told KTVU. "We'll be back here next year and very likely the year after I'm sorry to say because more people will have died."

"We'll be working every day, especially this summer, to try to assure that one candidate in this campaign will commit to getting all American troops out of Iraq…This is the only way this war will end… If the people demand it… That's what happened in Vietnam."

Authorities had detained dozens of protesters since the demonstrations began at San Francisco's Federal Reserve Building early in the day. Riot-geared San Francisco police officers forcibly removed and arrested seven protesters who had chained themselves to the Federal Reserve building.

Anti-war protester Alex Roselle said demonstrators targeted the Federal Reserve Bank to start the day to "call attention to the way the bank has been providing the foundation for the corporate pillaging of Iraq."

He said protesters hoped to turn the city into a "festival of resistance against the Iraq war, the occupation and the corporate greed that's been driving it all."

"For five years some people have struggled to end the war, and some gave up in despair," said Siri Margerin, 56, of San Francisco. "We have to keep doing everything and we have to keep doing it all the time."

Across the street a few hundred protesters banging drums and waving a large banner that read "Was it worth it?" blocked morning traffic with an impromptu parade.

"I think it's important to continue even if you don't see change right away," said marcher Liz Moore, 23, of Berkeley. "It shows the rest of world and other people in the U.S. that a lot of American people haven't forgotten."

More than 1,000 people then gathered in front of City Hall for an evening march against the war.

Randy Westbrook, who wore large American flag draped over his shoulders, said he was frustrated that such marches didn't seem to make a change, but thought it was still important because it one of "the few rights we have left."

"San Francisco is one of the few places where people are still awake," said Westbrook, 45, of Alameda. "I'm hopeful that someday more people will wake up. It's powerful when a lot of people get together and do this."

Across the bay in Berkeley, more than 100 anti-war protesters -- mostly students from Berkeley High School -- marched from a downtown park to a nearby Marine recruiting office Wednesday morning.

"We want the Marine recruiters to get out. They have no place in our schools," said Sareena Johnson, 15, a sophomore. "The schools are a place to learn, not a place to learn about joining the Army to die for a pointless war."

Earlier this year, the Berkeley City Council passed a controversial measure telling Marine recruiters they were unwelcome. Amid heavy criticism and threats by Republican lawmakers to withdraw federal funding, council members later moderated their position saying they oppose the war in Iraq but support the troops.

A handful of counterprotesters backing the recruiters in Berkeley waved Marine Corps and American flags.

"We're here because we support the Marines and their sacrifice and commitment to peace and serving our country. I believe they must be given our utmost respect," said Josh Curtis, 18, a freshman at the University of California, Berkeley, and a member of the Berkeley College Republicans.

Political action group MoveOn.org also was organizing candlelight vigils in several spots around the Bay Area, the Central Valley and in Southern California. Among those expected to speak against the war at a vigil in Los Angeles were veterans from World War II, the Korean War and the war in Vietnam.

In Sacramento, about 50 people gathered on the steps of the state Capitol to voice their opposition.

"From Guantanamo to Abu Ghraib, we've been grieving the actions of our own country for five long years," said Frank Graham, a poet who organized the rally.