How did the use of propaganda change during WWI and WWII?

Essentially, propaganda became more driven during both
World Wars.  The need for propaganda drove a machine that became an industry in of
itself.  For both sides in each war, propaganda became a critical element in molding
public opinion about each nation's approach to war.  Propaganda had always been in
existenc,e but both what was at stake in both World Wars made propaganda such an intense
focal point that all nations understood its importance.  It was meant to conceal the
truth about the wars, the massive death counts and horrific conditions.  Rather,
propaganda was used by all nations to continue support and enlistment in the wars,
itself.  In America, the use of Hollywood directors and actor to "push" the war effort,
especially so in the Second World War, as well as the development of boards of people
whose job was to ensure that public opinion stayed in favor of the war became
essential.  In Europe, propaganda became the defining element of ensuring that national
power structures would stay intact.  For example, Germany in World War II had an
impressive propaganda machine that was able to argue that Nazism was not only "the
answer," but the one for which the fight was worthy.  Italy's propaganda machine in
World War II also was able to advance Mussolini as a driving force behind Italian
strength.  In contrast, the lack of an effective propaganda machine in World War I for
Russia spelled the doom of the Czar and the Russian monarchy.