WALLA WALLA, Wash. — Retired Marine Corps Gen. James Mattis joined a growing number of Americans by taking part in the ALS Ice Bucket Challenge on Sunday, sources confirmed.

In a video uploaded to YouTube and later posted to Facebook, the former commander of Central Command turned academic is seen sitting in a folding camp chair next to a small swimming pool. As is customary for the event — which is meant to raise money for the ALS Foundation — Mattis begins by mentioning who nominated him to take the challenge before issuing his own.

“I guess I should thank Gen. Lloyd Austin, the commander of U.S. Central Command, for issuing this challenge,” Mattis said. “I guess this is his way of getting back at me for leaving him with an AOR that looks more like the inside of a well-used porta-shitter than a regional command, but hell, he’s a big boy, he should be able to handle it."