Riot police and the army were forced Monday to create a safe corridor for Catholic children to walk to school through a Protestant area - the violence underlined the deep-seeded hatred between the two communities.
A Catholic mother was struck in the face with a bottle and hospitalized as police pushed Protestants away from the disputed road in Ardoyne, a mostly Catholic district of north Belfast that has suffered frequent rioting this summer.
Most of the schoolgirls - among them children aged 4 and 5, attending their first day of school in brand-new red uniforms - were sent home early from Holy Cross Primary School in tears. A fleet of Catholic-run black taxis ferried them past lines of police in helmets and shields, while many Protestants shouted curses and insults.
"This looks like Alabama in the '60s," said Brendan Mailey, leader of a Catholic parents group that insisted on using the front door of the school, which lies in the small Protestant section of Ardoyne, rather than a rear entrance beyond the protesters' reach.
"It's beyond my worst nightmare. The abuse I heard was unbelievable. It was one of the most savage experiences of my life," said the Rev. Aidan Troy, a Catholic priest who was appointed governor of the school during the summer vacation break.
More than ever, Belfast is a place of walls and fences, which divide Catholics from Protestants, reports CBS News Correspondent Tom Fenton.
"People live apart, more separately," said Paul Bew, professor at Queens University in Belfast.
Bew has watched the communities grow apart as the walls have gone up.
"They have not made an investment in a new way of treating each other," Bew said. "They actually choose to live apart more, that's how they manage it."
Some of the walls fit in. They look good. Others, like one through a city park, are ridiculous.
Sometimes they are just plain ugly. On a good day, you can walk through, you can cross the sectarian divide. But there are bad days too.
On one street corner gasoline and matches ignited a fire that burned a couch and chairs piled high. It is a metaphor for Northern Ireland - apparent freedom, a sense of peace, and then it all goes wrong.
There are daily games of intimidation between the two religious groups. One day a group of joy riders thrash a stolen car next to one of Belfast's biggest walls. Their attempt to lure Protestants out from the other side doesn't work.
"They just want their neighbors from hell to shut up," Bew said.
But the Catholic youths will try again another day.
The most hotly debated issue between Catholics and Protestants is how to disarm the gunmen. Neither side trusts the other enough to make more than a token gesture.
But the unspoken issue the Protestant majority has always feared is about to hange Northern Ireland forever - the population time bomb.
CBS News has learned that unpublished census figures show the faster growing Catholic community is now almost half the population at 47 percent.
The long oppressed Catholic minority will soon be the majority, which is likely to generate more ugly scenes.
© MMI, CBS Worldwide Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report