MANAMA, Bahrain  More than 100,000 demonstrators packed central Pearl Square here on Tuesday in what organizers called the largest pro-democracy demonstration this tiny Persian Gulf nation had ever seen, as the monarchy struggled to hold on to its monopoly on power.

In a nation of only 500,000 citizens, the sheer size of the gathering was astonishing. Tens of thousands of men, women and children, mostly members of the Shiite majority, formed a ribbon of protest for several miles along the Sheik Khalifa bin Salman Highway as they headed for the square, calling for the downfall of the government in a march that was intended to show national unity.

“This is the first time in the history of Bahrain that the majority of people, of Bahraini people, got together with one message: this regime must fall,” said Muhammad Abdullah, 43, who was almost shaking with emotion as he watched the swelling crowd.

But for all the talk of political harmony, the past week’s events have left Bahrain as badly divided as it has ever been. Its economy is threatened and its reputation damaged. Standard and Poor’s lowered its credit rating this week, Bahraini authorities canceled next month’s Bahrain Grand Prix Formula One race  a source of pride for the royal family  many businesses remain closed, and tourism is down.