A longtime physician, Ronald Glasser made his greatest mark as a writer.

Serving in a military hospital during the Vietnam War, Glasser chronicled the lives of soldiers who'd suffered terrible wounds. His heralded and best-selling "365 Days" was one of the earliest books on the war's carnage.

"He wasn't afraid to call out what was really happening," said Joy Glasser, his former wife and partner until his death. "If there was an injustice, he would write about it."

Glasser, of Minneapolis, wrote seven more books while working as a Twin Cities pediatrician. He died Aug. 26 of natural causes at age 83.

Ronald Glasser was raised in Chicago, where his parents Sid and Ann owned a delicatessen. He got his undergraduate and medical degrees from Johns Hopkins University in Baltimore.

Glasser went to the University of Minnesota for an internship in pediatrics, followed by a residency at the U and the University of Illinois. He was certified as a pediatrician in 1968 – the same year he was drafted.

The U.S. Army sent Glasser to Camp Zama in Japan. His orders were to serve the children of military personnel, he told History.net in a 2011 interview. He ended up assisting in the operating room as casualties poured in from Vietnam.

"I had the nerve to tell our commander, 'I'm a pediatrician and haven't been in an OR for years.' ... He put his hand on my shoulder and said, 'That's OK, we'll just give you the little [expletive] wounds.'"

In the surgery ward, Glasser found the grist for "365 Days," which was published in 1971.

"They were 17- and 18-year-olds," he said in a 2013 interview with Open Road Media. "They were patients I was used to taking care of in my internship and residency, only now they were blown up, desperately ill and severely wounded. I looked around and realized the whole war was coming to me."

Glasser observed the human damage and talked at length with soldiers about their time in Vietnam. The unvarnished account won acclaim from critics and was nominated for a National Book Award in 1972.

Novelist William Styron noted Glasser's "dry, dispassionate, superbly controlled and ironic voice" in his 1972 review of "365 Days."

"It is a tribute to Glasser's great skill as a writer that from this most morally loathsome of wars ... he has fashioned a moving account about tremendous courage and often immeasurable suffering."

In a 2011 Wall Street Journal piece, playwright David Mamet wrote that "365 Days" is the "best book to come out of Vietnam."

Rough language in "365 Days" caused a Maine school board to ban the book as obscene. The resulting free speech case drew national media attention and ended with a federal judge reversing the ban.

Glasser continued writing books through 2011, including accounts of war and medicine in Iraq and Afghanistan. Medicine was at the core of his writing, which included magazine and newspaper articles.

"He would always say, you can only write about what you know," Joy Glasser said. "And he was always writing."

He was also working full-time as a pediatric kidney specialist in Minneapolis.

Besides Joy, he is survived by step-children Rachel, Benjamin and Aaron Silberman; a niece and two great-nieces. His brother Jack preceded him in death. Services have been held.