BAGHDAD — Tens of thousands of Shiites — a sea of women in black abayas and men waving Iraqi flags — marched to Najaf from Kufa yesterday, demanding that American forces leave their country on the fourth anniversary of fall of Baghdad. Streets in the capital were silent and empty under a hastily imposed 24-hour driving ban.

Demonstrators ripped apart American flags and tromped across a Stars and Stripes rug flung on the road between the two holy cities for the huge march, ordered up by radical Shiite cleric Moqtada al-Sadr as a show of strength not only to Washington but to Iraq’s establishment Shiite ayatollahs as well.

Mr. Sadr, who disappointed followers hoping he might appear after months in seclusion, has pounded his anti-American theme in a series of written statements, the most recent on Sunday when he called on his Mahdi army militia to redouble efforts to expel American forces and for the police and army to join the struggle against “your archenemy.”

The fiery cleric owes much of his large following to the high esteem in which Shiites hold his father, Ayatollah Mohammed Sadiq al-Sadr, who was assassinated in 1999 by suspected agents of Saddam Hussein. Mr. Sadr dropped from view before the start of the latest Baghdad security operation on February 14. U.S. officials say he is holed up in Iran. His followers insist he’s returned to Najaf.

Fearing suicide attacks, car bombings or other mayhem in the capital, Iraq’s generals ordered all vehicles off the streets for 24 hours starting at 5 a.m. yesterday, normally a work day. The capital was eerily quiet, shops were shuttered and locked and reports of sectarian violence fell to near zero.

Police and morgue officials reported finding just seven bodies dumped in the capital, only the second time the number of sectarian assassination and torture victims had dipped that low in the course of the Baghdad security operation. A total of 24 people were killed or found dead in the country yesterday, according to police and morgue reports.

A double line of police cordoned the marchers’ route to Najaf from Kufa, sister cities on the west bank of the Euphrates River. The holy places, 100 miles south of Baghdad, are a prime destination for Shiite pilgrims.

Among the snapping flags and giant banners, leaflets fluttered to earth, exhorting the marchers in chants of “Yes, yes to Iraq” and “Yes, yes to Moqtada. Occupiers should leave Iraq.”

Salah al-Obaydi, a senior official in Mr. Sadr’s Najaf organization, called the rally a “call for liberation. We’re hoping that by next year’s anniversary, we will be an independent and liberated Iraq with full sovereignty.”