At the start of the war the Free State infantry were already slightly better equipped than the anti-Treatyites, but what enabled them to drive the republicans from Dublin, Limerick, Waterford and Cork as well as many other small towns around the country in July-August 1922 was their possession of field artillery, of which the British donated 8 18 pounder field guns by 1922. The Four Courts, the republican headquarters in Dublin, a fortress-like 18th century monolith might have held out indefinitely if it had not been bombarded by four 18 pounder guns in July 1922.
In Limerick city similarly, had weapons been confined to small arms, fighting probably would have dragged on inconclusively for weeks in protracted fire fights in the streets. But once the Free State forces brought a single 18 pounder artillery piece to bear on the anti-Treaty headquarters in the Strand Barracks, blasting a breach in its walls, the republicans abandoned their positions throughout the city within a day.
The anti-Treaty IRA never possessed any artillery. Liam Lynch their Chief of Staff tried repeatedly to import mountain guns from Germany, but could not get either the cash or the contacts in Germany together. It is difficult to see, in any case, how they could have got past the Royal Navy blockade. The result was that, with rare exceptions, the IRA could not take even a well defended barracks let alone large towns, certainly after the autumn of 1922.