Watch highlights from Marie Yovanovitch’s testimony to the House Intelligence Committee in the impeachment inquiry.

On Friday morning, Marie Yovanovitch, the former U.S. Ambassador to Ukraine, laid out in plainspoken terms how she had been treated by President Trump and the Secretary of State, Mike Pompeo. Yovanovitch said that she had been “kneecapped” and “smeared” by the government that she was serving. She described her dismay and fear after she learned that Trump had told the President of Ukraine, Volodymyr Zelensky, in a phone call that she was going to “go through some things.”

“I was shocked and devastated that I would feature in a phone call between two heads of state in such a manner where President Trump said that I was bad news to another world leader, and that I would be going through some things,” she said. “It was a terrible moment.”

Yovanovitch—who spent more than three decades in the U.S. Foreign Service, with assignments in Somalia, Kyrgyzstan, Armenia, and Moscow—described an extraordinary series of events. While she was enforcing the U.S. government’s stated policy of countering corruption in Ukraine, she was undermined by President Trump’s personal lawyer, Rudy Giuliani. According to Yovanovitch, Giuliani worked with corrupt Ukrainians who were angered by Yovanovitch’s crackdown to force her out of her position. “What continues to amaze me is that they found Americans willing to partner with them,” she testified. “And working together, they apparently succeeded in orchestrating the removal of a U.S. Ambassador.”

Yovanovitch gave voice to the diplomats whom Trump and his Republican supporters have denigrated, presenting Americans with a choice of whom to believe. “Let me be clear on who we are and how we serve this country,” she said. “We are professionals. We are public servants who, by vocation and training, pursue the policies of the President, regardless of who holds that office.” She went on, “We take our oath seriously—the same oath that each one of you takes, to support and defend the Constitution of the United States against all enemies, foreign and domestic, and to bear true faith and allegiance to same.”

During questioning from Democrats, Yovanovitch described how she sought support from Pompeo but received none, and recalled her astonishment when she learned that President Trump had threatened her during his call with Zelensky. “A person who saw me actually reading the transcript said that the color drained from my face,” Yovanovitch said. “I think I even had a physical reaction.”

In an extraordinary step, Trump attacked Yovanovitch during her testimony. “Everywhere Marie Yovanovitch went turned bad. She started off in Somalia, how did that go?” he wrote on Twitter. “Then fast forward to Ukraine, where the new Ukrainian President spoke unfavorably about her in my second phone call with him. It is a U.S. President’s absolute right to appoint ambassadors.”

Adam Schiff, the chair of the House Intelligence Committee, read the tweets aloud to Yovanovitch. “What effect do you think that has on other witnesses’ willingness to come forward and expose wrongdoing?” he asked. Yovanovitch replied, “I can’t speak to what the President is trying to do, but I think the effect is to be intimidating.” Schiff later said that Trump was intimidating a witness—potential grounds for impeachment.

Yovanovitch will be attacked by Republicans. Her account will be questioned and undermined. Conspiracy theories will be trafficked about her. Those efforts will likely only bolster her account of being smeared, bullied, and intimidated by a President whom she has never met. On Friday morning, Yovanovitch’s testimony and Trump’s tweets captured how he conducts himself as President and how he treats those who work for him. The lesson of her story was a simple one: any public servant who gets in the crosshairs of this President will be destroyed by him. Yovanovitch’s testimony alone may not lead to the President’s removal, but she did great damage to Donald Trump.