Charles F. Gunther, a prominent Chicago collector, donated some items to the historical society. In 1920, the society purchased the remainder of the large history collection from his estate, with the intention of changing its focus from only a research institution into a public museum. Many of the items in Gunther's collection, in addition to Chicago, were related to Abraham Lincoln and the American Civil War. These include Lincoln's deathbed, several other pieces of furniture from the room where he died in the Petersen House, and clothing that he and his wife Mary Todd Lincoln allegedly wore the evening of his assassination. The collection also contains the table on which General Robert E. Lee signed his 1865 surrender to General Ulysses S. Grant, an official act that ended the American Civil War, at the McLean House in Appomattox, Virginia.