PRINCETON, N.J., NOV. 25 -- President Woodrow Wilson's behavior was affected by decreased blood flow to the brain during his oft-criticized and ultimately futile campaign to have the United States join the League of Nations, a historian says.

Records never made public show that Wilson was disabled by illness even before his 1919 stroke, during the critical period in U.S. history after World War I, said Princeton University history professor Arthur Link, editor of a series of volumes of Wilson's papers.

"It is one of the great tragedies of the 20th century," Link said in a recent interview. "The man who was most responsible for building support for the idea of a League of Nations was struck down just as his leadership was most needed. And he was struck down by events over which he had no control."

The 64th volume in the series, to be published in February, will reveal for the first time detailed medical records kept by Cary T. Grayson, Wilson's personal physician. Grayson's sons allowed Link to review the 70-year-old papers in May.

A Democrat, Wilson was president from 1913 to 1921. He suffered a devastating stroke in 1919 and died in 1924. He won the 1919 Nobel Peace Prize for his peacemaking efforts involving the League of Nations after World War I, but he failed to win U.S. support for the League, which fell apart before World War II.

Link said U.S. entry into the League of Nations could have altered history. "In a world with the United States playing a responsible, active role, the possibilities of preventing the rise of Hitler were limitless," Link said.

Wilson failed to get the Senate to ratify U.S. membership in the League because of what Link said was an uncharacteristic refusal to compromise. The Senate wanted guarantees that the United States would not be subordinate to the votes of other nations in case of war.

"In his normal, healthy state, Wilson would have found compromise with the large group of moderate Republicans," said Link. Instead, Wilson was robbed of "his ability at leadership, of his normal shrewdness and deftness, of his marvelous management skills. . . . He would lose his train of thought, and get confused. He would contradict himself, and eventually, blow his cool."

Against medical advice, Wilson, then 63, took his message directly to the people with a speaking tour of Western states in September 1919. The decision to go over the Senate's head angered the very lawmakers Wilson needed to court.

"The decision . . . was not only irrational but in the circumstances was bound to be futile," Link writes in the forthcoming book.

James F. Toole, director of the Stroke Center of the Bowman Gray School of Medicine in Winston-Salem, N.C., and Bert E. Park, a Springfield, Mo., neurosurgeon, analyzed the medical records for Link's book.

Toole wrote that the records indicate Wilson suffered from a disease of the carotid arteries in the neck, which hindered blood flow to the brain, and hypertension, which worsened his condition.

Park wrote that Wilson likely continued to suffer episodes of internal bleeding following a 1906 stroke. This could cause injury leading "in time to recognizable behavioral disturbances that typified Wilson from late 1919 onward," Park wrote.

Link said the records should lay to rest the theories that Wilson's problems were psychological.

"His failure in leadership instead derived from the ravages of disease," Link said. "History has judged Wilson as if he were a well man during this period."

In addition, the widespread belief that Wilson's wife ran the government after her husband's stroke is "pure nonsense," Link said. "It is a popular belief, but it has gotten more into the realm of legend than scholarship."

Grayson's journals show that Edith Bolling Galt Wilson served as a liaison between Wilson and his advisers, but that the government was run by his department heads, Link said.

Edith Wilson did make two crucial decisions following Wilson's stroke, Link said. She covered up the extent of Wilson's illness and thwarted suggestions that he resign. But Link said she long denied being an acting president and once told him she was "never interested in politics."