President Trump will deliver an in-person speech on Friday at the March for Life, an annual rally held in Washington protesting the legalization of abortion.

Trump will be the first president in history to appear at the march, one of the highest-profile events of the anti-abortion movement. March for Life is in its 47th year, having taken place every year since the passage of Roe v. Wade, the Supreme Court decision that legalized abortion nationwide.

Last year, Vice President Mike Pence made a surprise appearance at the march before roughly 100,000 attendees. The president also gave a message of support for the cause to attendees through a live video.

Jeanne Mancini, president of the organizing group, celebrated the announcement in a statement, saying Trump had been loyal to the anti-abortion movement.

“From the appointment of pro-life judges and federal workers, to cutting taxpayer funding for abortions here and abroad, to calling for an end to late-term abortions, President Trump and his administration have been consistent champions for life and their support for the March for Life has been unwavering,” she said. “We are grateful for all these pro-life accomplishments and look forward to gaining more victories for life in the future.”

The announcement landed on the anniversary of Roe. The anti-abortion movement, which was initially skeptical about Trump as the Republican nominee, now champions him as a president deeply committed to its cause.