Dr. George Tiller was a lightning rod for anti-choice forces because he performed late-term abortions—abortions after 21 weeks' gestation—for girls and women whose pregnancies had gone tragically, often life-threateningly, wrong. Some were women who wanted their pregnancies, but found out late in their terms that their baby had no brain, or that their twins were conjoined and could not survive, or that their baby was already dead. Others were rape victims as young as 10 or 11, some of them too young to even realize they had had periods.

About 200 men, women, and children gathered at the foot of the reflecting pool in Cal Anderson Park on Capitol Hill on Monday, June 1, to remember the life and mourn the death of Tiller, who was gunned down at his Wichita, Kansas, church last Sunday morning. He had been the target of an ongoing campaign of intimidation and harassment by anti-choice protesters at his home and clinic for the past three decades. He was 67.

Rose Mineer, who spoke at Monday's vigil, was one of Tiller's patients. Twelve years ago, when Mineer was 17, she was raped. "Through a not-uncommon welter of emotions, including shame and fear and confusion, I hid my pregnancy for four and a half months," she said Monday. By the time she came clean with her family and decided she wanted an abortion, it was too late for a conventional procedure, so she went to Dr. Tiller. "Looking back, the main emotion I remember feeling was a sense of safety and a sense of respect," she said. Tiller "spent an unimaginable number of hours with me over the week I was there. He was totally willing to take a sobbing 17-year-old and just hold her for half an hour while she cried. I never felt the least bit judged, and I think that's how my own personal healing began."

For countless women and girls like Mineer, Tiller was a godsend. His death leaves the U.S. with just two doctors who perform late-term therapeutic abortions—and a medical community in which providing late-term abortions will be seen as more dangerous than ever. "The clinics already knew that there was going to be an escalation, because that's historically what we've seen happen when we get a federal administration that believes in women's right to choose," NARAL Pro-Choice Washington director Lauren Simonds told me Tuesday. During the Clinton years, she said, there were six murders and 17 attempted murders of abortion providers and clinic staff. In the Bush years, there were zero.

So-called mainstream anti-abortion activists were quick to distance themselves from Tiller's murder, denouncing it, in the words of Operation Rescue director Troy Newman, as a "cowardly act" of "vigilantism."

If only that were true.

Tiller's murder was not an isolated act by a lone, crazed individual, as many officials, including President Obama, have insisted. It was the culmination of a terror campaign whose primary currency is intimidation. If you believe, as anti-abortion extremists do, that abortion is murder, then murdering in retaliation makes perfect sense. An eye for an eye. "When the so-called peaceful anti-choice protesters use language that dehumanizes and demonizes our providers by calling them murderers and baby-killers, they are inciting those who are more violent," Simonds said.

In a speech two weeks ago at Notre Dame, Obama encouraged both sides of the abortion "debate" to "open our hearts and minds to those who might not think like we do," to find "common ground" with our ideological opposites. The problem with such lofty supplications is that they presume each side is equally responsible for the contentiousness of the abortion "debate," and that if we'd just sit down and talk, we'd figure out a solution that works for everyone.

But there is no common ground—not when "common ground" is code for ceding women's rights to calm a storm we didn't create. And not when the difference between the two "sides" is that one side believes women have the right to determine their own destinies, and the other side believes women should cede control of our bodies to the state.

Terrorism only works if we give up that ground. You don't negotiate with terrorists, whether they're killing doctors or "only" threatening, harassing, and intimidating them.