On 14 April 1922 a group of 200 anti-Treaty IRA men occupied the Four Courts in Dublin in defiance of the Provisional Government. Michael Collins, who wanted to avoid civil war at all costs, did not attack them until June 1922, when British pressure forced his hand. This led to the Irish Civil War as fighting broke out in Dublin between the anti-Treaty IRA and the Provisional Government's troops. Under Collins' supervision, the Free State rapidly took control of the capital.

In Michael Collins and the Civil War, Ryle Dwyer sheds new light on Collins' role in the Civil War, showing how in the weeks and months leading to the campaign he secretly persisted with guerrilla tactics in border areas. This involved not only assassination but also kidnapping and hostage taking. In confronting those tactics on behalf of the British Winston Churchill engaged in similar behaviour, including killing and hostage-taking.

But until now much of this has conveniently been swept under the carpet of history.