With the results of the Election on June 16th, tipping well in favor of the Treaty Michael Collins, was under a new type of pressure, as leader of the Provisional Government. As the election results did not sit well with hard-line Republicans, Collins knew all too well that renewed violence could and would erupt at any moment. On June 22nd an event unfolded in London that lit the fuse which ignited the Siege of Dublin and in turn the Civil War.
“Reginald Dunne and Joseph O’Sullivan, both IRA men, assassinate Sir Henry Wilson, security advisor to Northern Irish Prime Minister James Craig, outside his house in London. The British Government, believing the killing was the work of anti-Treaty republicans, pressures Collins to attack the Four Courts.”https://centenaries.ucd.ie/1912-1923-timeline/#year-11
Two members of the IRA were arrested and hanged for the killing. There was still 6,000 British troops remaining in Dublin, which the British Government threatened to send back into action if Michael Collins did not remove the IRA (by then considered irregulars) from the Four Courts. Anti-Treaty IRA member, Leo Henderson was arrested by the pro-Treaty forces and in retaliation, pro-Treaty officer, JJ Ginger O’Connell was taken. Read more. Micheal Collins, under immense pressure, gave the anti-Treaty forces holding out in the Four Courts one last chance to surrender and hand back JJ Ginger O’Connell.
Northern Whig 23 June 1922