The Sunburst in the Fiannaíocht
The Sunburst flag has a literary origin, being described in the Fiannaíocht - the lays and narrative tales about Fionn mac Cumhail and the Fianna that were composed between the 14th and 18th centuries. The flag of the Fianna is called the Gal Gréine or the Scal Ghréine in the literature but the descriptions provided are poetic in nature and lack detail:
"Nochtar Gal Gréine re crann,
(The Sunburst is displayed on a mast,It would appear that the oldest extant illustration of the flag is that found in a manuscript which was written by Cathal Ó Luinín in the year 1731: it is shown there as a blue flag with a golden semicircle from which thirteen gold rays emanate.
The Sunburst and Fenianism
The Sunburst was used by nationalists from the first half of the nineteenth century although the Green Flag remained much more important throughout the period. One author writing in 1843 anticipated that both of these flags would be used after independence was achieved - one on sea and the other on land:
That the 'harp on the green' our land flag should be,
'Fenians' (a word derived from Fianna) was the name commonly applied to members of the Irish Republican Brotherhood, a revolutionary movement founded in 1858. As might be expected, the new movement used the Sunburst flag (alongside the Green Flag): Fenian flags had a green rather than a blue field and often showed the sun emerging from behind a cloud. Members of the IRB continued to operate in secret after the failure of the 1867 rising but had little occasion to use flags thereafter.
The Sunburst in the 20th century
When a nationalist youth-movement called 'Fianna Éireann' was established in 1909 it was a natural decision to readopt the Sunburst. The initial design used by Fianna Éireann was very similar to the drawing of 1731 but the flag gradually evolved into the modern design.
At the present time, the Sunburst is used by the Republican and the Irish-language movements. The sunburst motif also continues to be employed for military purposes, as in the colour of the army's military college shown below.