The power of a strike lies in its ability to cripple a company’s operations.

So when three clerical workers at a DHL facility outside Baltimore went on strike last week because of a dispute over benefits, it might not have sounded like a big deal.

But those workers are represented by the Teamsters, whose members have the right to honor a picket line of their fellow DHL colleagues if the picket line shows up outside their workplace.

And on Monday, the Baltimore picket line did show up, in Southwest Philly, which meant that about 100 DHL workers — people who unpack the planes, process packages, and deliver them around the city for the German international delivery company — didn’t cross the line and, instead, went home. They did the same on Tuesday and will do so throughout the week if the picket line remains.

It’s the first Teamsters “roving strike” that’s arrived in Philly in decades, and it comes at a time when strikes are on the rise. The last was likely in the ’70s, when the Teamsters were bargaining with the trucking industry over their national master freight contract. The roving strike is a powerful tool held by unionized workers employed by national companies, as the Baltimore workers of Local 355 can threaten to bring picket lines to other parts of the country. The Teamsters represent 5,000 U.S. DHL workers across 25 locals, including a newly organized group of clerical workers in Seattle.

Bill Hamilton, an international Teamsters vice president who oversees the Eastern region, said he couldn’t share which cities would be next or how long they would stay in Philly. Surprise is part of the strategy.

DHL hired temporary workers — “scabs,” in union parlance — to do the jobs of the 100 Philly DHL workers who did not cross the picket line. The workers didn’t join the picket line because the terms of their collective bargaining agreement don’t allow it, Hamilton said.

The three Baltimore workers who recently voted to join the union and are bargaining their first contract are fighting to get on the Teamsters health-care and retirement plan, but so far, DHL has not agreed and has instead offered them the company plan, which Hamilton said is more expensive. Health care is a major sticking point for workers these days, as unions fight for more affordable coverage.

The Baltimore outcome will not have any immediate bearing on the Philadelphia DHL workers, Hamilton said. Although any concessions made in one contract could eventually have implications for others. So why are Philly DHL workers walking off the job for their coworkers in Baltimore?

“An injury to one is an injury to all,” said Hamilton, repeating the old labor adage. “You see a company that’s this big and this rich fighting three employees and you fought your whole life to get your benefits. And these people are trying to get these benefits. ... They don’t think it’s fair.”

The workers are not getting paid by DHL so long as they are not crossing the picket line, Hamilton said, but they will get strike pay.

DHL declined to comment.

The DHL picket line in Philadelphia coincides with a national strike of nearly 50,000 General Motors employees represented by the United Auto Workers union, including a group of workers in Langhorne. An even bigger strike, of 80,000 Kaiser Permanente workers, is scheduled for next month. It’s expected to be one of the biggest strikes since 185,000 Teamsters walked off the job in 1997 at the United Parcel Service.