Attempts were made to agree a truce, including the Army Document, which called for political and military reunification and an agreed election which would produce a government supported by the whole country. Yet this was rejected by militant Irregulars, such as Rory O'Connor, and proved unsatisfactory to the British government, who were not prepared to accommodate any further with Republicans. The elections were eventually held in June, with pro-Treaty Sinn Fein receiving 58 votes and anti-Treaty Sinn Fein receiving 36 votes. The pro-Treatyites could now boast that they acted with the will of the people. On June 22^nd Sir Henry Wilson, military adviser to Northern Ireland, was assassinated outside his house in London. Wilson was shot dead by two IRB men who were probably acting on the orders of Collins. Collins probably saw the killing of Wilson as an opportunity to restore IRA and IRB unity through the question of Northern Ireland. The British were unaware of this and concluded that he had been killed by anti-Treatyite Republicans, receiving their orders from the Four Courts. Intense pressure was put on the Provisional government to remove Rory O'Connor and his followers from the Four Courts (the alternative was the British army returning to Ireland to do it themselves), and British military aid was offered. On June 26^th a group of Irregulars kidnapped the Free State Deputy Chief of Staff, General J.J. 'Ginger' O'Connell, in response to the capture of an Irregular by the Free Staters (as the pro-Treaty IRA became known). This proved to be the breaking point of the delicate 'peace'.

It is possible that the Provisional Government believed that the Republican garrison in the Four Courts did not have the support of many other anti-Treatyites, for example Eamon DeValera and his followers. The alternative to attacking them was the possibility of British troops returning to restore order to Ireland. On June 18^th at an Army Convention, the anti-Treaty IRA had split even further. Liam Lynch and the 1^st Southern Division set up a headquarters in the Clarence Hotel, separate to the IRA group in the Four Courts under Rory O'Connor. What Collins and the government may or may not have known is that by June 28^th, when the shelling began, the split in the anti-Treaty army ranks had been healed. Attacking the Four Courts would now almost certainly lead to Civil War.¹¹On June 27^th the evacuation of the Four Courts and the surrender of the Republican garrison was ordered. The garrison refused to surrender. Brigadier General Daly, who was commanding the Free State military operations, ordered the artillery to open fire. The Irish Civil War had begun.

War by the Irish on the Irish is the kind of political development which I observe with great pleasure-

Lord Birkenhead¹²

Practically every serious challenge in history against the constituted authority of a Nation which has been overcome, has been so overcome by prompt, effective, vigorous and utterly ruthless action-

Hugh Kennedy¹³

The political opponents of the Treaty who had so far remained separate from the anti-Treaty IRA, were forced to choose sides. The Four Courts garrison were shelled and surrendered on June 30^th. The first phase of the Civil War had echoes of the Easter Rising in 1916. The Irregulars had seized key buildings around Dublin such as the Gresham and Granville hotels. A field gun positioned on Henry Street fired at them and the buildings eventually caught fire. Cathal Brugha, in command at the Granville hotel, refused to surrender and was cut down by machine gun fire as he walked out of the blazing hotel. By July 5^th, most of O'Connell Street (Dublin's main street) was destroyed, 64 people were killed and 300 wounded. In reality, the anti-Treaty IRA had advantages in numerical and experience terms in the early months of 1922. That was the most likely period for successful military opposition to the Treaty.¹⁴ A Provisional Government source at the time estimated Republican IRA numbers as 12,900, with 6,780 rifles. However, they did not strike then and by the summer, the Free State had built up a considerable army and had organised it effectively. Continuous talks between both sides, and peace moves such as the failed Collins-DeValera pact meant that the country teetered for months on the edge of a knife: finally, with the shelling of the Four Courts, the knife cut, and outright war began.

The Irregulars reconsidered another attempt on Dublin through Blessington in Wicklow, and instead decided to fall back on Munster. The 'Munster Republic' was an area stretching from Limerick to Waterford, where support for the anti-Treaty IRA was strongest. Liam Lynch became leader of the Republicans following Rory O'Connor's surrender in Dublin. Mulcahy had released Lynch and Liam Deasy from prison in Dublin, in the belief that they would return to the countryside and try to get their anti-Treaty comrades to agree to peace. The 1^st Southern Division, of which Lynch was in charge, helped ensure that the Republican military effort was henceforth to be decentralised. The Four Courts garrison, who had advocated a Dublin-centred policy, had been arrested. The anti-Treaty IRA now operated out of Munster. But such a vast territory was impossible to defend with the limited number of soldiers. When the various Republican barracks came under pressure from the Provisional Government troops there was usually little attempt to hold the line. The Republicans frequently evacuated and burnt their garrison buildings in important centres such as Sligo, Castlebar, Clonmel and Waterford, when major confrontation appeared imminent. Meanwhile, the Provisional government began a huge recruitment drive and soon had an army of tens of thousands. Large unemployment at the time meant that it was an attractive job. For many ex-British soldiers, refused entry into the anti-Treaty IRA, it was a chance to continue a way of life to which they had grown accustomed.¹⁵ They were also able to borrow war materials from British garrisons still remaining in Ireland. They had the administrative machine at their disposal with a regular, if small, revenue emanating from it. On July 12^th the government created the War Council, appointing Michael Collins as Commander-in-Chief. Richard Mulcahy, the Minister for Defence, became his Chief of Staff, with General Eoin O'Duffy commanding the South-Western Division.

The government army attacked the Republicans in Munster by sea. A force which landed at Fenit on the north side of Tralee Bay went on to take Tralee town and over-run North Kerry. On July 21^st the Provisional Government Army used artillery to attack the Republicans in Limerick, in a similar tactic to the attack on the Four Courts garrison. The Republicans burnt the remaining barracks and retreated out of the city after sustaining some casualties, which handed control of Limerick to the Provisional Government. The government now controlled the estuary of the River Shannon and could send boats to patrol around Munster. Republican units in Clare and the midlands were henceforth cut off from their Munster colleagues.¹⁶ The fiercest fighting of the whole war then occurred in east county Limerick, where the Republicans initially defeated the government troops. But reinforcements from land and sea in early August eventually gave the Provisional Government an overwhelming numerical advantage and the Republicans were forced to retreat back towards Cork and Kerry. In late July Waterford City was taken by the government, effectively ending the Republican war in that area. The Free Staters also landed at Passage West in Cork Harbour and a combined sea and land attack ensured that the city was quickly evacuated, the Irregulars forced to retreat westwards. Many Republicans gave up the fight at this time and returned to their homes. By the end of August 1922, most of the major cities and towns were in the hands of the National Army. The Irregulars could clearly not hope to win the war, yet the fighting dragged on well into 1923. Ambushes, assassinations, reprisals, booby traps on roads and the torturing of prisoners were to follow.