BRENTWOOD, Calif. (AP) — A Northern California high school principal on Monday issued a public apology and handed a diploma to an Army reservist who was not allowed to wear his military uniform at his graduation ceremony last week.

Harland Fletcher, a private first class reservist in the U.S. Army, sat out the Friday ceremony at Liberty High School after the principal told him he would have to wear a cap and gown over his uniform if he wanted to participate.

Liberty High School Principal Patrick Walsh on Monday apologized to Fletcher, saying he takes full responsibility for the mishap.

“I made a mistake,” Walsh said. “We tried to fix it today.”

Walsh held a private ceremony at the high school in Brentwood, California, that was attended by Fletcher’s family and about 100 people, many of them military veterans in uniform who came out to support Fletcher.

Fletcher said he wants to send a message that the military shouldn’t be disrespected and that servicemen stand together.

“The uniform for me means honor, respect, integrity, and it stands for America’s freedom,” he said.