Wayne S. Cole, a leading scholar of the pre-World War II American isolationist movement. (Courtesy of University of Maryland )

Wayne S. Cole, a leading scholar of the pre-World War II American isolationist movement who wrote a sympathetic biography of one of its staunchest defenders, the aviator Charles A. Lindbergh, died Sept. 16 at a nursing home in Adelphi, Md. He was 90.

The cause was Parkinson’s disease, said his son, Thomas R. Cole.

Dr. Cole, an Army Air Forces pilot during World War II, spent much of his academic career teaching American diplomatic history at the University of Maryland. As an author, his focus was on the isolationist movement, which gained its strongest momentum in the years leading to the Japanese attack on Pearl Harbor on Dec. 7, 1941.

His maiden book was “America First” (1953), which like many of his works described the forces that animated the isolationist movement as a continuing presence in American politics. The Pulitzer Prize-winning New York Times journalist Anthony Leviero praised the work as “dispassionate and objective.”

Dr. Cole followed with “Senator Gerald P. Nye and American Foreign Relations” (1962), about the North Dakota Republican who was a leading noninterventionist between the world wars; “Charles A. Lindbergh and the Battle Against American Intervention in World War II” (1974); and “Roosevelt and the Isolationists” (1983).

The book that drew the most controversy was his Lindbergh biography, published shortly after the aviator’s death. Lindbergh became a sandy-haired hero to millions after his 1927 transatlantic flight, but his reputation never fully recovered from his association with the isolationists. He spoke at large rallies in the summer and fall of 1941, accusing Jewish media moguls and Jewish government employees of conspiring to lure the United States into war.

Dr. Cole, who gained rare access to the aging pilot and his papers, was generally regarded as kind to Lindbergh. Dr. Cole said enough time had passed for historians to realize that the isolationists, despite their unsavory reputation, had legitimate concerns. In his biography, he wrote that Lindbergh’s “warnings against excessive Presidential power, secrecy and deception in foreign affairs have striking parallels with American concerns a generation later.”

He added that President Franklin D. Roosevelt’s attacks against the isolationists — depicting most of them as Nazi sympathizers — were similar to those wielded by Sen. Joseph McCarthy (R-Wis.) against perceived Communists in the early 1950s.

The isolationist movement attracted a sizable fringe group of fascists and neo-Nazis who accused the Roosevelt administration of being in the pocket of Jews and the British, but it also drew sympathizers including industrialist Henry Ford, producer Walt Disney, poet e.e. cummings and even the socialist Norman Thomas.

The movement spread across campuses where young men were likely to be cannon fodder in any coming war. Gerald R. Ford supported the cause, as did future Peace Corps director R. Sargent Shriver Jr. (who would head the Peace Corps) and Gore Vidal.

Dr. Cole wrote that although Lindbergh’s offensive comments tended to draw the most attention, the aviator had much to say about the costs of blood and treasure in entering the war.

“Treating Lindbergh sympathetically was something new,” said Christopher M. Nichols, an assistant professor of history at Oregon State University and an authority on the isolationist movement.

“Charles Lindbergh put great faith in [Cole] and his work, granting him access to his papers of that period and detailing his role in its ‘Great Debate,’ ” over whether the United States should intervene in World War II, said A. Scott Berg, who won the Pulitzer Prize for his 1998 biography of Lindbergh.

Some reviewers faulted Dr. Cole for failing to address why Lindbergh used such inflammatory language during the 1941 rallies — even though the aviator knew how his comments would come across — and why Lindbergh never issued a retraction.

Wayne Stanley Cole was born in Manning, Iowa, on Nov. 11, 1922. He was a 1946 graduate of Iowa State Teachers College, now the University of Northern Iowa. He studied American diplomatic history at the University of Wisconsin and received a master’s degree in 1948 and a doctoral degree in 1951.

Dr. Cole taught at the University of Arkansas and Iowa State University before starting his 27-year tenure on the University of Maryland faculty in 1965. He was a past president of the Society for Historians of American Foreign Relations and a recipient of its lifetime achievement award.

Survivors include his wife of 63 years, Virginia Miller Cole, and their son, Thomas R. Cole, both of Silver Spring, Md.

“Cole did a lot to show the domestic grounding of foreign policy questions,” Nichols said. “I think that the questions and that history is really with us today. There are real reasons to be cautious about the use of U.S. power around the world.”

Strains of support for isolationism persist today in debates about the faltering national economy versus intervention in foreign crises, including the Syrian civil war. While Dr. Cole believed that the roots of isolationism go back to America’s founding, he thought that the movement could never prevail in an era of greater international cooperation and economic interconnectedness.

“It isn’t likely to revive,” Dr. Cole told the Hartford Courant in 1991. “The world and American society and the economy are so radically different now.”