‘September 1913’ is a poem by W. B. Yeats (1865-1939). It describes Ireland in the month of September 1913, as the title suggests, and sees Yeats lamenting the condition of Ireland at that time. Before we offer an analysis of the poem, here’s a reminder of the text of ‘September 1913’.
September 1913
What need you, being come to sense,
But fumble in a greasy till
And add the halfpence to the pence
And prayer to shivering prayer, until
You have dried the marrow from the bone;
For men were born to pray and save:
Romantic Ireland’s dead and gone,
It’s with O’Leary in the grave.
Yet they were of a different kind,
The names that stilled your childish play,
They have gone about the world like wind,
But little time had they to pray
For whom the hangman’s rope was spun,
And what, God help us, could they save?
Romantic Ireland’s dead and gone,
It’s with O’Leary in the grave.
Was it for this the wild geese spread
The grey wing upon every tide;
For this that all that blood was shed,
For this Edward Fitzgerald died,
And Robert Emmet and Wolfe Tone,
All that delirium of the brave?
Romantic Ireland’s dead and gone,
It’s with O’Leary in the grave.
Yet could we turn the years again,
And call those exiles as they were
In all their loneliness and pain,
You’d cry, ‘Some woman’s yellow hair
Has maddened every mother’s son’:
They weighed so lightly what they gave.
But let them be, they’re dead and gone,
They’re with O’Leary in the grave.
In summary, ‘September 1913’ is a poem in which Yeats laments the loss of ‘Romantic Ireland’. Each of the four stanzas of ‘September 1913’ ends with the same repeated refrain: ‘Romantic Ireland’s dead and gone, / It’s with O’Leary in the grave.’ (The final stanza slightly departs from this wording.)
Who was ‘O’Leary’? John O’Leary (1830-1907) was an Irish patriot who was sentenced to twenty years of penal servitude in 1865 (although he was freed four years after his conviction, on condition that he didn’t return to Ireland until the twenty years of his agreed sentence had passed, so he became an exile). Yeats knew O’Leary, who acted as a sort of mentor and father figure to Yeats. O’Leary was an extremely 
cultured man who knew a great deal about the history and folklore of Ireland; he even lent Yeats some books, so this explains the significance of O’Leary in the poem.
Yeats elsewhere praised O’Leary’s talent for ‘self-expression’ and ‘personality’: for a budding poet, as Yeats was when he met O’Leary following the latter’s return to Dublin from exile in 1885, such qualities were exactly the sort of things to inspire a following, and Yeats, Maud Gonne, Katharine Tynan, and others learned a great deal from O’Leary in the late nineteenth and early twentieth century.
The first stanza focuses on money and prayer: Yeats is arguing that Irelanders are too concerned with petty financial matters and dogged religious duty, and are not alive to the cultural issues which make Ireland unique. The second stanza contrasts modern Irelanders with those names of legend which walked the land in ages gone by: the names of people from Irish legend and history which every child knew (before they grew up to be adults obsessed with money and religion).
Picking up on this, the third stanza actually names some of these figures. The reference to ‘wild geese’ is not to the birds, but an allusion to Irish exiles (like John O’Leary), but earlier exiles, who served in Catholic armies in Europe following the Treaty of Limerick in 1691 (which led to the Irish Jacobite armies being transported to France, following their defeat at the Battle of the Boyne in 1690; this became known as the ‘Flight of the Wild Geese’).
Next, Yeats names some of these heroes of old, but focuses on a slightly later period of Irish history, from the late eighteenth century. Is this (i.e. modern Ireland) what these brave men fought and died for? Yeats asks with barely concealed disappointment and disgust. Edward Fitzgerald (1763-98), a lord, was a leader of the Irish Rebellion of 1798 (an early uprising against British rule in Ireland). Fitzgerald had died while resisting arrest (he was shot in the shoulder and later died of his wounds). Robert Emmet and Wolfe Tone were also involved in the same rebellion.
The fourth and final stanza of ‘September 1913’ highlights the hypocrisy of many modern Irelanders: they revere and honour these Irish heroes of the past, but if such men as Fitzgerald and Wolfe Tone were around now, in 1913, people would dismiss their patriotism as romantic idealism: they’d say that such men had had their heads turned by a woman’s pretty blonde hair and that was why they were fighting. Yeats concludes the poem by effectively giving up the fight: that old Ireland that believed in such romantic patriotism as a just cause is ‘dead and gone’, just like O’Leary (who had died six years before).
According to Edward Larrissy in his note to ‘September 1913’ (in the excellent edition of Yeats’s work, The Major Works including poems, plays, and critical prose (Oxford World’s Classics)), the poem was actually written in the month of September 1913 and reflects that month in Irish history: Larrissy writes that the poem is Yeats’s acknowledgment that he, and other Irish people, are living through a critical moment in Irish history. ‘Petty materialism’ (Larrissy’s phrase) is threatening Ireland’s aim to build a national culture of its own.
In the last analysis, ‘September 1913’ is a poem that responds to a turning point in early twentieth-century Ireland. If everything would be ‘changed, changed utterly’ by the Easter Rising of 1916 (as Yeats puts it in his poem ‘Easter 1916’), then ‘September 1913’ reflects Yeats’s own dismay at the turn away from the old Ireland built on romantic ideals towards a new, more pragmatic but more culturally devoid Ireland. The bloody events of 1916 and afterwards would consolidate Yeats’s worst fears.