Kendall fell ill with a digestive illness and insomnia in the summer of 1869. On August 2, he traveled to New York City to visit a nephew. He fell ill with what he believed was a common cold, but by the time he returned to Washington, D.C., on August 14 he was bedridden. As his wife was preparing to move the household into the William Stickney mansion at 6th and M Streets NW, Kendall resided at the home of Robert C. Fox, his son-in-law. Three weeks later, and still bedridden, Kendall moved into the Stickney mansion. Kendall was unable to eat and was in great pain. He called his illness "bilious fever", but it was more likely cancer of the liver and the stomach. The pain was so great, Kendall considered suicide, and he remained bedridden until the end of his life.