Zachary Taylor
As a commander in the Mexican American War, Zachary Taylor ended the dictatorship in Mexico and established a constitutional republic. Like many commanders of his day, he became the 12th president of the United States. But on the 4th of July, he became ill after eating cherries and milk and died in the White House 4 days later.
His physicians blame his illness and death on cholera, which was common in the summertime, but conspiracy theorists suggest he was poisoned.