Ash Carter, an Abington native and Harvard professor with a degree in theoretical physics who served as Defense Secretary under the Obama administration, died of a heart attack on October 24 aged 68. Nancy A. Youssef and Michael R. Gordon reported his loss in The Wall Street Journal.

“President Obama and I relied on Ash’s fierce intellect and wise counsel to ensure our military’s readiness, technological edge, and obligation to the women and men of the greatest fighting force in the history of the world,” said President Joe Biden, reflecting on his relationship with Carter when he was Vice President.

Carter served as Obama’s last defense chief between 2015 and 2017. He played a key role in the U.S. campaign against the Islamic State terror group and opened up combat positions to women.

He continuously pushed for closer ties between Silicon Valley and the Pentagon. At the time of his death, he was serving as director of the Belfer Center for Science and International Affairs at John F. Kennedy School of Government at Harvard University.

“He believed that his most profound legacy would be the thousands of students he taught with the hope that they would make the world a better and safer place,” said his family.

Read more about Ash Carter in The Wall Street Journal.