In the proclamation issued during the Easter Rising, it states "In every generation the Irish people have asserted their right to to national freedom and sovereignty; six times during the past three hundred years they have asserted it in arms."
What are the six times referred to here?
Irish Rebellion of 1641 Irish landowners, who had seen their rights reduced and had their land-holdings threatened by the Plantation of Ireland, sought to take control of the island in order to force King Charles I to submit to their demands. They attempted to take Dublin on 23rd October 1641, but failed, but succeeded in taking forts in the north of the island, largely through use of a forged Royl Commission which claimed to give them power to act. Thanks to the outbreak of the English Civil War, the rebellion dragged on, and the Irish established a provisional government, the Confederate General Assembly, which was held in Kilkenny. It was not until the Cromwellian conquest of Ireland between 1649 and 1653 that English control over the island was fully restored.
The Williamite War in Ireland When King James II of England was removed by the Glorious Revolution, a Jacobite uprising in support of James' rule broke out in Ireland. James II himself landed in Kinsale on 12th March 1689, and was welcomed into Dublin, where the Irish Parliament had declared that he was still king. On 1st July 1690 James II and his forces were defeated by those of William III at the Battle of the Boyne, and James II fled to France. The harsh peace terms offered by William III caused the Irish Catholic landowners to continue fighting until 3rd October 1691, when a more favourable treaty (the Treaty of Limerick) was concluded.
Irish Rebellion of 1798 Led by the Society of United Irishmen, the rebellion began in Dublin on 24th May 1798 and quickly spread to other parts of the country. The main defeat of the Irish Rebellion occurred at the Battle of Vinegar Hill near Enniscorthy in Wexford on 21st June 1798, before finally being ended on 14th July 1798. It's worth noting that a great deal of the support for the rebellion came from Presbyterians, as all non-Anglican Protestants had been discriminated against in the same way that Roman Catholics had by the Penal Laws.
Ribbon Society/Tithe War The Ribbon Society was a collection of Irish Catholic tenants who conducted violent acts between 1813 and 1855, though never part of a formal rising. The Tithe War was a small scale conflict between 1831 and 1836 where Catholic farmers resisted (occasionally violently) the collection of Tithes by the Church of Ireland (an Anglican organisation). There was a lot of overlap between membership of the Ribbon Society and resistance to tithes.
Young Irelander Rebellion The Repeal Society was a society that sought to repeal the 1800 Act of Union that had brought Ireland into the United Kingdom. From this, a group known as Young Ireland broke away in 1847, founding a group called The Irish Confederation. The society is actually the one that created the flag of today's Ireland. The Young Irelanders sought an independent Irish republic founded on the principles of the liberal nationalism expressed in Europe at the time. Fearing a nationalist uprising like those experienced throughout Europe, the government of the United Kingdom suspended habeas corpus in Ireland in order to allow the arrest and detention of "such Persons as he or they shall suspect of conspiring against Her Majesty's Person and Government". In order to avoid arrest, the Young Irelanders (William Smith O'Brien, Thomas Francis Meagher, and John Blake Dillon) were forced to act, and marched to Ballingarry, where they barricaded themselves. On 29th July, the police approached Ballingarry, but finding the Commons barricaded by the Young Irelanders and their local supporters, barricaded themselves into two nearby farmhouses. William Smith O'Brien attempted to negotiate with the police, but while doing so was fired upon by one of the constables, causing an exchange of fire that lasted a couple of hours. Two of the Young Irelanders' supporters were killed, and the Young Irelanders fled. John Blake Dillon fled to France and ultimately to the USA. Thomas Francis Meagher was arrested and transported to Tasmania and then escaped to the USA. William Smith O'Brien was transported to Tasmania and following his release lived in Brussels.
Fenian Rising The Fenian Rising was an attempt by the Irish Republican Brotherhood to establish an independent Irish Republic. There were failed risings in Dublin, Kerry, Cork and Limerick in early 1867. Thanks to the British having a number of informers, a number of the leaders of the risings were arrested before the risings could take place.
Sources:
Hansard: SUSPENSION OF THE HABEAS CORPUS (IRELAND).
Alvin Jackson: The Oxford Handbook of Modern Irish History