Hundreds of thousands of anti-Syrian demonstrators flooded the capital Monday in the biggest protest ever in Lebanon, surpassing the turnout for an earlier pro-Damascus rally organized by the Islamic militant group Hezbollah (search). In a show of national unity, Sunnis, Druse and Christians packed Martyrs' Square as brass bands played and balloons soared skyward.

The rally, perhaps the biggest anti-government demonstration ever staged in the Arab world, was the opposition's bid to regain momentum after two serious blows: the reinstatement of the pro-Syrian prime minister and a huge rally last week by the Shiite group Hezbollah.

Protesters — some bused in from across Lebanon (search) — jammed Martyrs' Square and spilled into nearby streets. They chanted, sang and shouted in a mix of the Arabic accents of the country's regions, demanding Syrian troops depart and that their government be purged of Damascus' influence.

The turnout was broader than earlier opposition protests, with more Sunni Muslims in particular joining the Christians and Druse (search) who have formed the bulk of past anti-Syrian rallies. Even some Shiites joined in.

"We came to liberate our country. We are coming to demand the truth," said Fatma Trad, 40, a Sunni woman wearing a headscarf. "I've been watching it all on television for the past month. Today, I wanted to be a part of it."

There was a party atmosphere on the Mediterranean seaside square, where many young faces were painted with the red and white colors and green cedar tree symbol of the Lebanese flag. And there were signs poking fun at Syria.

"Papa don't preach, I'm in trouble deep," read one, with a picture of Syrian President Bashar Assad apparently looking shamefaced at his late father, Hafez Assad. "Take them with you," another sign sneered at the departing Syrians, with pictures of Lebanese President Emile Lahoud and other Damascus allies.

As Syria pulls its troops toward the border for an eventual withdrawal from the country it has controlled for decades, both the pro-Syrian government and the opposition have been whipping up crowds in a duel of people-power one-upmanship.

Each side seeks to show it has the louder voice of the people behind it. For the opposition, Monday's rally was vital to demonstrate it could claim the street after Hezbollah's March 8 rally drew a half-million people. The Shiite group has organized large rallies in the past, but its showing last week was a sign of its determination to make sure no future Lebanese government would consider peace with Israel or pressure Hezbollah to disarm.

In recent days, opposition ads for Monday's rally have been running on television, and activists in towns and villages arranged buses to the capital. E-mails and telephone text messages referred to Prime Minister Omar Karami's claim that the Hezbollah demonstration showed the government had the support of the majority.

"Prove him wrong," the messages flashed across cellphones and computers.

The opposition is demanding the withdrawal of Syrian troops, the ouster of Syrian-allied security chiefs and an international inquiry into the killing of former Prime Minister Rafik Hariri and 17 others in a bombing many Lebanese blame on Syria and its allies. The opposition has rebuffed calls to join a new government until its demands are met.

Many in the crowd Monday also demanded the removal of President Lahoud.

"We want freedom. It is now or never!" said Rose Touma, a 55-year-old Christian, raising the Lebanese flag in one hand and, in her other, a picture of Hariri. "I thank God that I'm alive to witness this beautiful day."

The red and white flags were everywhere. A giant one 100 yards long was rolled out, and protesters waving flags in their hands climbed towering cranes and scaffolding along the walls of the Mohammed al-Amin Mosque.

One couple brought their 11-month-old baby, who slept in a stroller covered with the Lebanese flag. "This is how he expresses himself," said his smiling father.

Unlike some of the previous anti-Syrian protests, security forces did not attempt to block demonstrators or hinder their movement.

The only solemn moment was at 12:55 p.m., when protesters marked the exact time Hariri was killed Feb. 14. The silence was broken only by tolling church bells and the flutter of flags.

There were no official estimates of the crowd size, but Lebanon's leading LBC TV station and some police officers estimated it at about 1 million. An Associated Press estimate put the number at least 800,000. Either way it was the biggest demonstration ever in this country of 3.5 million.

Cars and buses carrying protesters jammed the main roads into Beirut, forcing some people to leave their vehicles and walk. Druse descended from the Chouf and Aley mountains east and southeast of the capital, Christians came from the heartland in the northeast and many Sunni Muslims came from Tripoli, Dinniyeh and Akkar. Others traveled to Beirut from Hariri's southern hometown, Sidon.

Many were particularly galled by Lahoud's reinstatement of Karami as prime minister last week — a slap in the opposition's face since anti-Syrian protests had forced him to resign only 10 days before.

The large Sunni turnout also suggests many in the community were shaken by the size of the Hezbollah rally and wanted to show their own strength. Shiites make up about a third of Lebanon's population, and Hezbollah is the country's best armed and best organized faction. Sunnis form the country's third biggest group after the Shiites and the Christians.

"We have everything to gain and nothing to lose anymore," said Ahlam Honeini, a Sunni mother of five who said she was ignoring her doctor's orders not to stand for long periods of time because of a slipped disc.

Responding to newspaper reports that authorities might ban protests, opposition leader Walid Jumblatt said: "No one confronts an entire people that wants freedom." And opposition lawmaker Fares Soeid said: "We will continue until all our demands are met."

Syria has been Lebanon's main power broker since sending troops to its neighbor in 1976 to help quell a civil war. The troops, at times numbering more than 35,000, remained after the war ended in 1990.