What 20th Century Wars Did Soldiers Get Medals For?

For another way to think about war, I turned to U.S. military campaign service medals.  The reason I used this as a database is that they are authorized by Congress.  And not every kind of conflict counts for a medal.  For example, veterans' groups have lobbied for a Cold War medal, but that legislation has not passed.  So this is, in essence, a U.S. government database of military service in conflicts that the United States has participated in. 

My information about medals came from John E. Strandberg and Roger James Bender, "The Call of Duty": Military Awards and Decorations of the United States of America, 2nd. ed.