Peadar Kearney [Peadar Ó Cearnaígh]

Peadar Kearney (Irish: Peadar Ó Cearnaígh; 12 December 1883 – 24 November 1942) was an Irish republican and composer of numerous rebel songs. In 1907 he wrote the lyrics to The Soldier's Song (Amhrán na bhFiann), now the Irish national anthem.

http://en.wikipedia.org/wiki/Peadar_Kearney