Charles M. English, a multilingual agent who worked undercover with the Central Intelligence Agency, died Aug. 9 at his vacation home in Raymond, Maine. He had pulmonary fibrosis and had had a stroke. His primary home was Springfield, Va. He was 86.

English was a doctoral student in linguistics at the University of Wisconsin when he was drafted into the Army in 1942.

He was quickly assigned to the Office of Strategic Services, the forerunner of the CIA, and remained with the OSS until 1947, when the CIA was formed.

English knew 10 languages so proficiently, his son Charles said, that he could do crossword puzzles in them. He used his linguistic facility during 17 years of overseas postings with the CIA, including several as an undercover agent.

After moving to Belgrade in the late 1940s and learning Serbo-Croatian, he established the agency’s first office in Yugoslavia.

He spent five years in Munich on the Russian desk of the CIA’s Radio Liberty, which was broadcast into the Eastern bloc. He also served seven years as director of the U.S. defector program in Germany, supervising interviews and logistical arrangements with potential defectors to the West.

When he retired in 1979, English received the CIA’s Career Intelligence Medal.

He was born in Newburyport, Mass., and graduated from high school in Wilmington, Vt., in 1935. He did an additional year of studies at Deerfield Academy in Deerfield, Mass., before entering Middlebury College in Vermont, from which he graduated in 1940 as the class valedictorian. English received a master’s degree in French from the University of Wisconsin in 1941.

From 1946 to 1948, he taught French at George Washington University.

The son of a minister, English was active in the Christian Church denomination, which later became part of the United Church of Christ. He established an English-language Sunday school in Yugoslavia and served as a lay minister in military chapels overseas and at churches near his summer home in Maine.

He served six years on his denomination’s national United Church Board for World Ministries.

English also volunteered with the Boy Scouts and with a historical society in Maine.

As a lifelong fan of the Boston Red Sox, English attended Game Four of the World Series in St. Louis on Oct. 27, when the Red Sox won their first World Series title since 1918, the year before he was born.

Survivors include his wife of 55 years, Marjorie Wadsworth English of Springfield and Raymond; three children, Cathryn Reed of Fairmont, W.Va., Ralph English of Rochester, N.Y., and Charles M. English Jr. of Washington; five grandchildren; and a great-granddaughter.