Is W.H. Auden really a modernist poet?

Absolutely. I think actually that W. H. Auden is one of
the first names that springs to mind when I think of the word Modernism. Let us remember
that it was Auden that entitled Modernism "The Age of Anxiety" which came to define the
spirit of Modernism so strongly and the way that the aftermath of World War I raised
serious existential questions about humanity and notions such as "civilisation" and
"progress" which are captured by Modernist writers.

Many
critics argue that Auden created poetry that it is difficult to separate. He was
responsible for the creation of a body of work rather than separate entities, which
created an "Audenesque" atmosphere that allowed the thriving of certain ideas and
concepts that we relate to Modernism: the seeming anarchic chaos that descended upon the
world after Victorian stability and the widespread disenchantment with human
institutions.