STAUNTON, Va. -- While U.S. troops were fighting in World War I in the summer of 1918, President Woodrow Wilson underwent treatment for a breathing problem in a hushed episode that foreshadowed worse health troubles to come.

The White House doctor, Cary T. Grayson, later recounted the incident to his wife in one of a slew of newly public documents that show how far Wilson's innermost circle went to conceal his frail condition amid major world events.

" The patient is progressing most satisfactorily, so far, and I have good reasons to hope for a most beneficial result. It has been a big undertaking. . . . No one knows anything about it except Miss E., Miss Harkins, Hoover -- It is one secret that has been kept quiet, so far, and I think it is safe all right now," the doctor wrote Alice Grayson in a July 16 telegram...