They demanded that the government enact laws that put to death anyone who blasphemed Islam.
They called for mandatory Islamic education for all in this secular Muslim nation.
They wanted a ban on statues, and the words "absolute trust and faith in the Almighty Allah" reinstated in the constitution.
They declared that men and women should not be allowed to mix freely in this country of 150 million.
And they vowed they would not leave until their demands -- 13 in all -- were met.
The ensuing confrontation was violent. And bloody.
Country's direction at stake
What is happening in Bangladesh is a push and pull between two forces to determine the future direction of the country.
In February, thousands and thousands of youths held a month-long sit-in in another part of the capital, Shahbag, demanding the death penalty for those who took part in war crimes during Bangladesh's bloody battle for independence from Pakistan.
Many of those accused of war crimes now hold prominent position in Islamist parties.
The rallies, led by youths and fueled by social media, also tried to achieve something else: a ban on extreme fundamentalist parties.
But Bangladesh is also the fourth most populous Muslim country in the world.
And the radical elements of the religion were not going to sit by idly as those rallies grew.
The Islamists let their presence known with larger and larger rallies and strikes, first in cities outside Dhaka and then in the capital city.
Each time they came out, police officers with batons followed.
Clashes ensued. Properties were destroyed. Lives were lost.
The Islamists' tactic has been to turn the criticism on its head: By criticizing them, they seemed to say, you criticize Islam.
They called the Shahbag participants "anti-Islamic atheists" who deserve death for defaming the religion but who are protected by the government.
And so, when the Hefazat-e-Islami protesters gathered Sunday, that was one of their main demands: put to death these "atheists."
Battles for hours