The presidency of Ulysses S. Grant began on March 4, 1869, when Ulysses S. Grant was inaugurated as the 18th president of the United States, and ended on March 4, 1877. The Reconstruction era took place during Grant's two terms of office. The Ku Klux Klan caused widespread violence throughout the South against African Americans. By 1870, all former Confederate states had been readmitted into the United States and were represented in Congress; however, Democrats and former slave owners refused to accept that freedmen were citizens who were granted suffrage by the Fifteenth Amendment, which prompted Congress to pass three Force Acts to allow the federal government to intervene when states failed to protect former slaves' rights. Following an escalation of Klan violence in the late 1860s, Grant and his attorney general, Amos T. Akerman, head of the newly created Department of Justice, began a crackdown on Klan activity in the South, starting in South Carolina, where Grant sent federal troops to capture Klan members. This led the Klan to demobilize and helped ensure fair elections in 1872.

The United States Department of Justice (DOJ), also known as the Justice Department, is a federal executive department of the United States government tasked with the enforcement of federal law and administration of justice in the United States. It is equivalent to the justice or interior ministries of other countries. The department is headed by the U.S. attorney general, who reports directly to the president of the United States and is a member of the president's Cabinet. The current attorney general is Merrick Garland, who has served since March 2021.