Willie was the third son of Abraham Lincoln and Mary Todd Lincoln. He died of an illness at the age of 11. He was named after Mary's brother-in-law Dr. William Wallace.Willie and Tad became ill in early 1862. While Tad was not as badly effected, Willie's condition fluctuated from day to day. The most likely cause of the illness was typhoid fever, which was usually contracted by consumption of contaminated food/water. The White House drew its water from the Potomac River, along which thousands of soldiers and horses were camped. Gradually Willie weakened, and his parents spent much time at his bedside. Finally, on Wednesday, February 20, 1862, at 5:00 p.m., Willie died. Abraham said, "My poor boy. He was too good for this earth. God has called him home. I know that he is much better off in heaven, but then we loved him so much. It is hard, hard to have him die!"