In 1865, the Confederacy's civilian government disintegrated in a chaotic manner: the Confederate States Congress adjourned sine die, effectively ceasing to exist as a legislative body on March 18. After four years of heavy fighting and 620,000–850,000 military deaths, all Confederate land and naval forces either surrendered or otherwise ceased hostilities. The war lacked a formal end, with Confederate forces surrendering or disbanding sporadically throughout most of 1865. The most significant capitulation was Confederate general Robert E. Lee's surrender to Ulysses S. Grant at Appomattox on April 9, after which any lingering doubt regarding the war's outcome and/or the Confederacy's prospect for survival was extinguished, although another sizable force under Confederate general Joseph E. Johnston did not formally surrender to William T. Sherman until April 26. Contemporaneously, President Lincoln had been assassinated by Confederate sympathizer John Wilkes Booth on April 15, 1865. Confederate President Jefferson Davis's administration declared the Confederacy dissolved on May 5 and Davis himself acknowledged in later writings that the Confederacy "disappeared" in 1865.