Short answers, pulled from the story.
The River Queen was chartered by the U.S. Department of War and served as General Ulysses S. Grant's private dispatch boat on the Potomac River in 1865. It hosted the Hampton Roads Conference on the 3rd of February 1865, an unsuccessful attempt to negotiate an end to the American Civil War. Abraham Lincoln also used the vessel to meet with Sherman, Porter, and Grant in March 1865 to discuss war strategy.
The Hampton Roads Conference took place in the saloon of the River Queen on the 3rd of February 1865. During the conference, the River Queen was lashed alongside another ship, the Mary Martin.
The River Queen was built at Keyport, New Jersey in 1864. It was initially owned by Alfred Van Santvoord.
In July 1911, newspapers reported that the River Queen burned to the water's edge following the explosion of a signal lantern on board. By that time the vessel was among the oldest side-wheelers still in service and was being used as an excursion boat on the Potomac River.
After the war, the River Queen operated between Providence and Newport, Rhode Island under the Newport Steamboat Company. By 1871 it was sailing routes serving Martha's Vineyard and Nantucket, and by March 1886 it was one of four steamers in the New Bedford, Martha's Vineyard, and Nantucket Steamboat Co. fleet.
The River Queen appears in the 2012 film Lincoln, where the Hampton Roads Conference is depicted and several scenes take place aboard the vessel. Those scenes were shot on an indoor set rather than an actual steamboat.