During the Civil War, President Abraham Lincoln saw a benefit to censoring freedom of speech and the press. He issued an order that did so. His reasons aligned with those listed later on in World War I & II, which was to avoid the leaking of troop movements and locations. Even when the war began in 1861, Lincoln censored telegraph communications from war correspondents on the battlefield.¹ 
Throughout the war, censors and restrictions were forced onto press in the Northern States. Should a journalist oppose the draft or divulge information about military movements without approval, he ran the risk of being detained and put on trial. Members of the cabinet — and occasionally even the president himself — ordered the arrests of various newspaper editors and press sites, including editors from the New York World.¹
Lincoln even suspended habeas corpus during the time of the war. Habeas corpus was an act first put into place in England, which states that a person under arrest must be brought before a judge in a court of law.³ Without this writ in place, the government could arrest editors and journalists freely should they determine that any published content puts the war effort in jeopardy — and more often than not, the government restricted the “free” press without any involvement from a judge.¹
Although censorship of the press may come from a place of concern for the war effort, doing so unconstitutionally impedes on the freedoms of well-meaning Americans. Free speech and free press is one of the most important things to this country.
¹ The First Amendment Encyclopedia – The Civil War