One poem in which the Anglo-Irish poet W.B. Yeats uses mythology (in this case the old myths of Ireland) is the beautiful 'Song of Wandering Aengus.' Aengus was a god-like being who became associated with love and poetry. Irish books tell of a young man of great charm and attractiveness, represented by four flying birds which circle his head like a crown. Some tellers of the story speak of the birds representing kisses. Aengus falls deeply and madly in love with a sweet gentle maiden, but then loses her and cannot find her again. He tries everything, almost going mad in his quest - he even gets his mother,then his father to look for her. In Yeats' version she is eventually found again but he has Aengus spend years (getting older and older) looking for her.
One way William Butler Yeats uses history is to embed it in the language of his poetry and plays. During the struggles against England that ensued following Parnell's downfall, when Gaelic was receiving broad attention and revival, Yeats, as he tells in his 1923 Nobel Prize Speech, and his associates discovered, with the help of Lady Gregory, that rural peasants told the old stories of Ireland in a language that was "in a form of English which has much of its syntax from Gaelic, much of its vocabulary from Tudor English." Yeats found that their speech was "our most powerful dramatic instrument." As a result of studying and employing the speech of this peasantry, Yeats incorporated the fibers and the stories of history into his writing through modelling their speech.
An auxiliary point to this is that the theater begun by Yeats, Lady Gregory, financial subscribers and the players and others with whom Yeats worked, was caught up in the history unfolding in that moment and they placed themselves in the position of being the "somebody" who, in the midst of "some kind of revolutionary frenzy" of ill-judged actions and reactions, "must teach reality and justice." As a result, Yeats felt compelled to turn more and more to "become always more realistic, substituting dialect for verse, common speech for dialect."
One of the prominent themes in Yeats's work is what is generally referred to as the theme of the "impact of fate and the divine on history." Yeats valued the realities of history as keys to understanding. At a young age, he turned away from the Christian religion but always pursued a quest for knowledge and understanding of the divine. He immersed himself in the studies of mythology, spiritualism, Theosophy and philosophy. He developed his own theory of historical determinism affected by divine fate, which propounded the idea that historical events had been preordained by the divine: Events were as they were because they could have been nothing else according to the dictates of divine fate. Yeats's complex system, shown by interlocking gyres, details the development of the human soul and its reincarnation(s). He also believed that divinely determined historical fate could be revealed to mankind if and when the human and the divine interact. This unity of history, mythology, the divine and divine fate appear in his poetry in a literal form, in an abstract form and in the form of symbolic representations. Some commonly identified works of Yeats where this is readily recognized are "Leda and the Swan" (1923), where this unity appears literally; "The Second Coming" (1919), where it appears in the abstract; and "Sailing to Byzantium" (1926), where it appears in symbolic representation in the mosaics.
[For additional information on Yeats's Nobel Prize Speech, see NobelPrize.org where you can read his whole speech.]