Longstreet enjoyed a successful post-war career working for the U.S. government as a diplomat, civil servant, and administrator. His support for the Republican Party and his cooperation with his old friend, President Ulysses S. Grant, as well as critical comments he wrote about Lee's wartime performance, made him anathema to many of his former Confederate colleagues. His reputation in the South further suffered when he led African-American militia against the anti-Reconstruction White League at the Battle of Liberty Place in 1874. Authors of the Lost Cause movement focused on Longstreet's actions at Gettysburg as a primary reason for the Confederacy's loss of the war. Since the late 20th century, his reputation has undergone a slow reassessment. Many Civil War historians now consider him among the war's most gifted tactical commanders.