Propaganda and censorship
Propaganda was widely used by the Allies and Central Powers alike during the First World War. This could take many forms, from books, newspaper articles and posters to cinema and photography. Propaganda emphasised the Government 'line' and exposed the failings of a given enemy.
Strict censorship, and the official licensing of military intelligence, was imposed by both sides during the Great War.
One example of censorship was the interception of letters sent home from the Front by the Censor's Office. The contents were checked not merely for military secrets but also for any adverse comments about the morale of the troops. Propaganda and censorship went hand in hand.