Propaganda
Propaganda is often used during wars.  There it can be very useful.  Sometimes it keeps the people of a country happy  telling them that their country is fighting well and telling them how important it is that the enemy is defeated. Sometimes it tries to make people hate the enemy. The information could tell people that the enemy is evil or make them seem not human. Sometimes a government gives propaganda to the enemy  telling them that the war is going badly for them and that they should stop fighting.