Mathew Brady was a photographer who covered the American Civil War. He took some of the most iconic photographs of that period, including the Battle of Antietam, the Siege of Yorktown, and the Battle of Gettysburg. His photographs captured the brutality and carnage of the war and helped shape public opinion about the Civil War. He is considered to be one of the most influential photographers of the American Civil War and his work continues to be studied and appreciated today.