W. Byron Forbush II, the longest-serving headmaster of Baltimore’s Friends School whose tenure oversaw the social unrest of the 1960s and a doubling of the school’s enrollment, died Thursday at his home in Lutherville after an illness, family members said.

Dr. Forbush was 87 and had spent much of his life at the Quaker school in North Baltimore. He arrived there as a preschooler and retired after 38 years as headmaster in 1998.

“Rarely has any institution been as synonymous with its leader as Friends was with Byron,” Matt Micciche, current head of Friends School, wrote Saturday in an address to students and alumni.

Dr. Forbush followed his father, Bliss Forbush Sr., in the role of Friends headmaster. Mr. Forbush Sr. led the school from 1943 to 1960. Combined, the father and son ran Friends for more than five consecutive decades.

With a wry humor and forthright nature, Dr. Forbush maintained a tireless daily schedule as headmaster. Most days he wouldn’t linger over lunch, and his routine peanut-butter sandwich became well-known around campus. “It’s very efficient,” he told the Friends School magazine in 1998. “I don’t enjoy sitting down to one- to two-hour lunches.”

In the late 1980s, Dr. Forbush recruited Ken Smith to run the Friends middle school. Smith’s job interview included dinner at a neighborhood tavern, Swallow at the Hollow.

“If you’re trying to recruit somebody, you’d think you’d take them to a fancy restaurant,” Smith said. “He wanted to see if I was a down-to-earth guy and not fancy and pretentious. Quakers are down-to-earth people, and they value honesty and forthrightness — he exemplified all those qualities.”

As one of seven children born to Mr. Forbush Sr. and his wife, Laverne Hill Forbush, a homemaker, William Byron Forbush II graduated from the Friends high school in 1947 and attended the Johns Hopkins University, where he studied “history and lacrosse,” as he told the Friends School magazine.

An All-American attackman, Dr. Forbush played on Johns Hopkins’ storied 1950 championship lacrosse team and graduated the following year.

He then earned a master’s degree in teaching at Harvard University and was drafted into the U.S. Medical Corps in the Korean War.

As a Quaker, he believed in pacifism. “I told them I would not carry a gun,” he told the Friends magazine. Instead, he spent about two years serving in the burn ward at Fort Sam Houston in San Antonio, Texas, and cared for wounded American soldiers.

“I became convinced that every young person should spend some time serving,” he told the magazine.

He later earned a doctorate in education from Columbia University.

Dr. Forbush spent one year as a teacher and administrator at Friends Academy in Long Island before returning to Baltimore as headmaster in 1960.

The following years brought sweeping social change to the campus. The private school was desegregated in 1955 and Dr. Forbush led efforts to bring in African-American students and teachers. During his tenure, he established an internship program for African-American teachers and helped raise scholarship money for students from low-income families.

In the 1970s, as American youths were pushing back against authority, Friends School boys revolted and refused to wear their required neckties. Girls at the school protested against wearing skirts. Other students, outraged by conditions of farm workers, organized a lettuce boycott on campus, said Mr. Micciche.

“He really had to navigate the birth of student activism and questions of authority,” Mr. Micciche said. “Those years, especially the 1960s and 1970s, would have been a very, very challenging time.”

Meanwhile the school, which was founded in 1784, experienced significant growth. During Dr. Forbush’s tenure from 1960 to 1998, enrollment doubled to nearly 1,000 students in preschool through 12th grade. The school budget swelled to $11 million from $500,000. High school tuition jumped to $10,960 from $825.

During that period, Dr. Forbush saw his own role as headmaster change from educator to CEO with a staff of about 200 people.

“I came back to the same school that I had graduated from,” he told The Baltimore Sun in 1996. “This is not the same school, and by the way, it should not be.”

He also served 41 years on the board of trustees for the Quaker-founded Sheppard Pratt Health System. And the last 18 years, he served as the board chairman. He embraced the hospital’s history and sought to preserve it with a walking tour and exhibition on medical treatment. He wrote histories of the hospital and adopted the role of archivist, categorizing thousands of pages of records.

“The archives were in disarray,” said Dr. Steven Sharfstein, former president of Sheppard Pratt Health System. “There was a great deal of work he did to insure the history of Shepherd.”

He was honored in 1998 with the Distinguished Alumnus Award from Johns Hopkins.

In April that same year, Friends School celebrated his retirement during an emotional ceremony. He received a ceramic table set with 1,000 tiles painted by students or teachers. Dr. Forbush said the hardest part about leaving would be moving off campus — his home since childhood.

Arrangements for a memorial service for Dr. Forbush have not been finalized.

He was preceded in death by his first wife, Ann Farquhar. He remarried in 2003 and is survived by his second wife Elizabeth Forbush, of Lutherville.

In addition to his wife, he is survived by daughter Marjorie Forbush of Wooster, Ohio; sons William Forbush III of Watertown, Mass., and Norman Forbush of Baltimore; stepchildren Elizabeth Wingard of Greenville, S.C.; Katherine Manzanares of Colorado Springs; and Michael Simons, of Charlotte, N.C.; five grandchildren, eight step-grandchildren and one great-grandchild.

tprudente@baltsun.com