Connolly first came to Ireland as a member of the British Army. The strong Irish presence in Edinburgh stimulated Connolly’s growing interest in Irish politics in the mid 1890s, leading to his emigration to Dublin in 1896 where he founded the Irish Socialist Republican Party. He spent much of the first decade of the 20th century in America, returning to Ireland to campaign for workers' rights with James Larkin. A firm believer in the perils of sectarian division, Connolly campaigned tirelessly against religious bigotry. In 1913, Connolly was one of the founders of the Irish Citizen Army. During the Easter Rising he was appointed Commandant-General of the Dublin forces, leading the group that occupied the GPO. Unable to stand due to wounds received during the Rising, Connolly was executed while sitting down. He was the last of the leaders to be executed.
Ba le hArm na Breataine a tháinig Ó Conghaile go hÉirinn ar dtús. Ainneoin go ndeachaigh sé ar ais go hAlbain bhí an oiread de mhuintir na hÉireann i nDún Éideann gur méadaíodh a spéis i bpolaitíocht na hÉireann i lár na 1890idí. D’fhill sé ar Bhaile Átha Cliath in 1896 agus bhunaigh sé Páirtí Poblachtánach Sóisialach na hÉireann. Chaith sé blianta ina chónaí i Meiriceá ag tús an fichiú haois. Tháinig sé ar ais go hÉirinn le troid ar son cearta na n-oibrithe in éineacht le James Larkin. Chreid Ó Conghaile go láidir gur bhain contúirtí móra le seicteachas agus throid sé go dian in aghaidh bhiogóideachta reiligiúnaí. In 1913 bhí Ó Conghaile ar dhuine de lucht bunaithe An Airm Chathartha. Le linn Éirí Amach na Cásca, ceapadh mar Cheannfort Ginearálta é ar fhórsaí Bhaile Átha Cliath agus bhí sé i gceannas ar an ngrúpa a ghlac seilbh ar Ard-Oifig an Phoist. Gortaíodh é san Éirí Amach, agus mar gheall air sin b’éigean é a mharú agus é ina shuí ar chathaoir. Ba é an duine deireanach de na ceannairí a cuireadh chun báis.