The Board in question refers to the Military Commission established during the U.S. Civil War, specifically after the assassination of President Abraham Lincoln. This commission was responsible for trying and sentencing eight individuals accused of conspiring to assassinate Lincoln and attack Secretary of State William Seward. The trial, also known as the Trial of the Conspirators, took place from April 27 to July 7, 1865, at the Old Capitol Prison in Washington, D.C. The commission was chaired by Army Judge Advocate General Joseph Holt. The proceedings were notable for their publicity and the importance of the accused's roles in the assassination plot. Six of the eight defendants were found guilty and sentenced to death, including Mary Surratt, the only woman charged. Four were hanged on July 7, 1865. The trial marked a significant event in U.S. history, reflecting the nation's efforts to bring justice following the tragic assassination of its president.