Monday, April 24, 1916 was the beginning of the Easter Rising, an armed resistance by the Irish against oppressive British rule. The movement was quickly squashed by the British, but in the aftermath support for an independent Republic of Ireland became more solidified. An article in Wikipedia states: “A few months after the Easter Rising, W. B. Yeats commemorated some of the fallen figures of the Irish Republican movement, as well as expressed his torn emotions regarding these events, in the poem Easter, 1916. Some survivors of the Rising went on to become leaders of the independent Irish state and those who died were venerated by many as martyrs.” (You can read Yeats' poem here)
“The Foggy Dew,” an Irish ballad commemorating the Easter Rising, was written in 1919 by Canon Charles O’Neill, a parish priest from County Down. The song is performed her by Sinead O’Connor with The Chieftains for their album The Long Black Veil.