John Bull's Other Island by George Bernard Shaw was written in 1904. Shaw, himself Irish, wrote it for the Abbey Theater in Dublin, but Yeats and Synge didn't think it fit with their vision of a new Irish national literature, especially in the way it satirized Ireland rather than evoked positive images of Irish culture. Thus it was actually first produced on November 1, 1904 in London at the Royal Court Theater. The single best place to discover more about the context of the play is in Shaw's own 60-page preface which addresses precisely the social and political situation of Ireland and how it influenced Shaw in construction of the play.
The key factor in this period was that Ireland was ruled by England. While the Irish were Roman Catholic the English were mainly Protestant, and while the Irish, especially in rural areas, spoke Celtic as a first language, the English spoke English. Wealth was concentrated in small Protestant ascendancy of English aristocrats surrounding Dublin. There was a strong Irish independence movement, which led up to the Irish War of Independence of 1919 to 1921.
The play contrasts the enterprising, efficient, and unimaginative character of the economically successful English with the romantic imagination of the Irish, and in the marriage of Nora and Broadbent suggests that the two cultures can both benefit from each others' strengths and compensate for each others' weaknesses.