They came armed with rocking chairs and knitting needles, clad in the standard issue uniform of long skirts and sun hats adorned with pins and flowers. They sipped from porcelain tea cups and exchanged photos of their grandchildren.

But for the setting — a set of railroad tracks outside the Seattle terminal where a controversial oil rig is currently docked — and the chains linking their gently rocking chairs, it could have been any casual meeting of old-fashioned matrons.

But these women were not your grandmothers’ grandmothers. They were “Raging Grannies,” and they were mad.

“As oceans rise before our very eyes/no time for dumb debate, we hope it’s not too late” they sang to the tune of “Frère Jacques.” “We must act. We must act.”

A few hours after setting up camp near Seattle’s Terminal 5 to protest the Arctic-bound Royal Dutch Shell oil drilling rig, all five Raging Grannies were arrested. Seattle police cut through the duct-taped “lock boxes” that bound their arms and loaded them into a van to the department’s Southwest Precinct. After processing, they were sent home and told they’d be notified of their charges within a week.

“It was quite a different kind of arrest,” said Shirley Morrison, a Seattle great-grandmother just two months shy of her 93rd birthday and the oldest of the five women arrested Tuesday. “They were nice to us.”

Morrison speaks with authority: she’s been arrested three times before, she told The Washington Post in a phone interview. Morrison attended her first protest more than half a century ago, at a rally to help people of color get jobs at a local shopping center. Since then Morrison has chained herself to nuclear facilities, rallied at the World Bank and helped bring shopping centers to a standstill. Now she’s a hardy, veteran activist with wispy white hair and glasses, active in the frequent Seattle demonstrations against Shell. She has a thoughtful, genteel way of speaking, pronouncing the “h” in “what” and referring to more junior protesters as “wonderful young people.”

In 1995, Morrison helped found the Seattle Raging Grannies — the local branch of an international group of progressive-minded grandmothers. At demonstrations, (Morrison calls them “actions”) she wears her standard granny uniform of sunhat and flowing skirt, wielding every one of her 92 years like a weapon. Being a Raging Granny is all about making the most of an older woman’s moral clout.

“Grannies are best equipped to make public corrupt things that have been hidden,” reads a manifesto on the Raging Grannies Web site. “… From the most ancient times, the strong, wise, older women were the ones who advised, mediated and fought for what was right.”

That seemed to be the case at the Seattle protests Tuesday, where the grannies outlasted their younger counterparts.

The Shell rig “Polar Pioneer,” which was recently approved for exploratory oil drilling the Arctic, has been the target of frequent demonstrations over the past month. Environmental groups say that drilling poses the risk of a catastrophic spill and could threaten the fragile Arctic environment, but the Bureau of Ocean Energy Management said it considered potential environmental and social impacts before granting Shell permission to move forward with the plan.

On Tuesday morning, group of younger protesters had gathered with oil drums and signs on an overpass near where Morrison and her compatriots were rocking, according to the Seattle Times. When Seattle Police’s Apparatus Response Team pulled up with a truck full of saws, jackhammers and other heavy-duty tools to help dislodge them (Seattle, being Seattle, has to have a special unit devoted to removing protesters who have chained themselves to things), the younger activists walked away.

But the grannies stayed put. The police milled around for a few hours, Morrison said, while they figured out what to do with the women. Meanwhile, the women chanted songs they’d composed and set to familiar tunes, replacing “She’ll be coming ’round the mountain” with “We’re radical environmentalists” and “My Bonnie lies over the ocean” with “You’ve polluted the air and the water.” Some even sang a rap they had written for the occasion.

“Some of the younger generation don’t get the older songs,” Morrison told The Post. “So we try to come up with new ones.”

Eventually, police  covered the women in tarps to protect them from debris and sawed through the ropes, tape and chains that tied them together. (Morrison was the only woman not bound — she has a great-grandchild on the way and was working on knitting the kid a sweater.) The women grinned and waved at photographers as the officers cut them loose. Nearby, a crowd of onlookers chanted “Rock on, grannies,” according to the Seattle Times.

It was a “visual victory” for the grannies, Southwest Precinct Capt. Pierre Davis told the Seattle Times.

The tangible benefits of the protest were more fleeting. A railway spokesman told the Times that the protest disrupted train traffic for only about 3 hours, from 6:30 to 10 a.m. And a Shell spokesman wrote in an e-mail to Reuters that work on the Polar Pioneer continues as planned.

But Morrison is optimistic about the effort.

“We can do something about it because we always have in the past,” she said, cheerfully.