BRENTWOOD, Calif. — 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.

Liberty High School Principal Patrick Walsh apologized to a Harland Fletcher, a private first class reservist in the U.S. Army, and took full responsibility for the mishap at a ceremony where many waved American flags.

Fletcher 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.

"I made a mistake last Friday night, and I don't mince words. I deeply regret what occurred," Walsh said.

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 their fellow serviceman.

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.

The 18-year-old high school graduate said he did not want to make the ceremony about him, but rather highlight what the military is about.

"I didn't really need the apology, but I wanted to send a message that the military is about friendship — brothers and sisters standing together, not just letting someone trample over us," Fletcher said.

Sgt. Duane Edwards, a Vietnam War veteran, attended the ceremony with the rest of the Marine Corps League of Brentwood. He said he wanted to show his support to the graduating senior after he heard about what had happened on the news.

"What was done was completely in violation of the law," Edwards said. California law gives Fletcher the right to wear his uniform during graduation.

Fletcher's wife, Valentina Fletcher, and their 6-month-old son shared in the special moment.

"I think the support is tremendous," Valentina said. "It shows how everyone is here to make sure that the uniform doesn't get disrespected again."

Fletcher is uncertain what he will do in the near future but said he plans to have a long career in the military.