Okay so Dadaism happened during WWI when artiest, intellectuals and writers refused to accept what the world was doing pretty much. So they became non-artists and non-writers because nothing else in the world seemed to matter, so why would the arts? They used their art as a protest, an outrage, that when people reacted to it at all they were entirely encouraged. It was based on nonsense, and were determined to only follow one rule, which is to never follow known rules. Dadaism was known for starting the surrealist movement. They re-mixed the world into new strategies for example claiming a urinal as a fountain. As a student I think this is a useful thought process. When one starts to remix the world, their world changes, and anything can become art.
Dadaism collapsed on itself when it started to become an accepted form of art.