And when they poured sugar into the petrol tanks of bulldozers, torched Mayor Teddy Kollek's car and spread tar over the grave of Theodor Herzl, founding father of Zionism, it was on the instructions of their operational commander, Yehuda Meshi-Zahav.
Mr Meshi-Zahav has waited a long time for the war of the graves, in which his people are attempting to defend burial sites threatened by construction. As a five-year-old on the mean streets of Mea She'arim, the Jerusalem enclave where ultra-orthodox Jews retreat from the alien influences of the secular world, he stoned cars on the sabbath. Since then he has been in and out of police cells - charged, for example, with putting rats in the homes of pathologists during Haredi protests over autopsies.
Last week Meshi-Zahav, 31, practised his newest insurgency tactics - learned, he says unashamedly, from the Arabs. The men in black hats, as well as their women and children, hurled cement blocks at police, burned tyres and overturned cars. And all the while they shouted 'intifada Yehudi' - Jewish intifada - and 'Nazis, Nazis'. Police responded intifada-style, with plastic bullets and tear gas.
It was the Haredim's biggest battle for years; bigger even than the 1987 Sabbath Cinema Wars. The enemy was the same: the Zionist Jews who are building a secular state and acting, according to the Haredim, against Jewish law. But this time the cause was greater. In the past the religious-secular battles in Jerusalem have largely been over the future of the living city: this battle is over the future of the city of the dead.
In proportion to its living population, Jerusalem probably has more dead buried in its soil than any other city in the world. In recent years archaeolgists have uncovered 750 Jewish burial caves, dating back to the Second Temple period 2,000 years ago. To disturb Jewish bones is, say the Haredim, a sacrilege of the highest order.
According to Mr Meshi-Zahav, the alert first went out about two months ago that graves were about to be defiled at two key building sites in Jerusalem - French Hill, where a new road was being built, and Mamilla, where a shopping complex was planned. Archaeologists were expected to move in to take away the ancient bones. Mr Meshi- Zahav is co-ordinator of the Eda Haredit, a body representing 10,000 ultra-Orthodox families. It incorporates the notorious anti- Zionist Natura Karta group, which last week offered sanctuary in Mea She'arim to the Palestinian deportees.
The group has a grave-watching unit called Atra Kadisha, employing 25 full-time Haredi agents who shadow bulldozers and archaeologists wherever they threaten to touch a Jewish bone.
When the alert first went out a 24-hour Haredi guard was placed on the two sites and police radio was monitored. Mr Meshi-Zahav prides himself on good contacts with the police and they occasionally call him in to help with crowd control. But last Saturday his contacts failed. Out of the blue, Atra Kadisha agents informed him that archaeologists were moving in on the Mamilla site, thus wrong-footing the Haredi commander, who had been preparing for protests at the French Hill site. Mr Meshi- Zahav says two Haredi undercover agents, dressed as secular Jews, discovered the trick by infiltrating archaeologists' lines.
The Haredim had been told that if the Sabbath siren went off they were to move en masse to the French Hill site. In an emergency, Haredi activists planned to put up posters featuring the code word nahash, meaning snake, directing people to French Hill. There were no contingency plans for a move on Mamilla.
'We had to think quick,' said Mr Meshi-Zahav. 'We sent out cars with loudspeakers telling people to get down to Mamilla. Then the police arrested the drivers, so people with hand-held loudhailers spread the word. By 3am, thousands were out on the streets. It was incredible. They were all following orders, burning garbage cans, fighting police.'
It was a great battle, but the Haredim lost, never getting past the police cordon to prevent the bone removal. However, the riot brought a ruling from the Supreme Court that excavations should halt until the merits of the Haredim case over the French Hill site had been examined.
Since the election in June of Prime Minister Yitzhak Rabin, most ultra-Orthodox parties have been out in the political cold. Only one religious party, Shas, is part of Mr Rabin's coalition and this has caused jealousy among the others. Secular critics of the Haredim say the grave protests have been fuelled deliberately to embarrass Shas and force it to pull out of the coalition.
Mr Rabin certainly appears to believe such a ploy might lie behind the protests. Fearing a threat to his coalition after the row over the Palestinian deportees - and perhaps to curry favour with the other religious parties - he has convened a ministerial committee to find a compromise over the future of the French Hill graves.
If such a compromise is not reached it is certain that Mr Meshi-Zahav will be ready for another stand. He now has a list of 1,000 crack Haredim who have signed an agreement saying they will risk their lives to protect the French Hill graves. 'Before they signed, the rabbis said they had to get permission from their wives,' he said. 'Mine knew what she was in for when she married me. If the authorities think the battle of Mamilla was big, they haven't seen anything yet.'