Today marks the 100th anniversary of the beginning of the Civil War.

The conflict lasted almost a year, cost 2,000 lives, and devastated the country. The cost of the physical destruction has been put at £50m in 1922 values.

Six months earlier, the leaders of the Irish War of Independence signed a Treaty with Britain, that ended the war and offered limited independence inside the British Commonwealth.

There would be no Irish Republic, the new entity would be called the Irish Free State.

All members of the new Irish parliament, the Dáil, would have to swear an oath of allegiance to the British crown.

The Dáil narrowly voted to accept the terms of the Treaty, but those opposed to it believed too much had been conceded to the British, and that the ideals of the Republic had been betrayed.

The new Provisional Government saw the Treaty as a beginning not an end, and the freedoms that had been won could be expanded upon.

Reconciliation proved impossible. The anti-Treaty wing of the Irish Republican Army renounced its allegiance to the Dáil and the Government, and declared itself the defender of an Irish Republic.

Both sides prepared for war. The new Free State Army received substantial arms shipments from Britain.

The anti-Treaty IRA stole weapons from the Free State Army, the new Civic Guard police force, the British Army and Royal Navy.

The anti-Treaty IRA seized the Four Courts complex in Dublin as its new headquarters.

The Provisional Government held off from reacting, partly out of hope that reconciliation was still possible, but also because the Free State Army was not ready for battle.

Read more - Civil War 1922: Darkness descends

Pressure from the British to act grew, while the government itself knew its credibility was on the line as long as the strength of the anti-Treaty IRA increased.

There were faint hopes that war could be avoided. The government tried to get Britain to accept a new Free State Constitution that took away many of the conditions of the Treaty, and some senior IRA leaders believed this could indeed be a way out of the crisis.

But Britain would not budge on the terms of the Treaty.

The General Election of June 1922 saw a decisive victory for the pro-Treaty cause, as well as for Labour, farmers' candidates and Independents, sending a message from the people that they wanted no war.

But almost immediately these hopes were dashed.

On 22 June, one of Britain’s most senior army officers, Field Marshal Henry Wilson, was shot dead outside his home by two members of the London IRA.

Responsibility for the assassination has never been proved, but the British immediately blamed the anti-Treaty IRA in the Four Courts, and gave the Irish government an ultimatum: deal with them, or we will.

The Provisional Government had just received this ultimatum when, in retaliation for the arrest of IRA officer Leo Henderson, the IRA kidnapped a Free State Army general, JJ O’Connell.

The government believed time had finally run out on the chances for peace, and ordered the army to prepare to fire on the Four Courts, unless the IRA garrison surrendered.

The anti-Treaty IRA men inside the building were given almost no time at all to consider the demand, before the Free State Army opened fire with borrowed British artillery, at just after 4am, on Wednesday 28 June 1922.