The biggest single loss for the IRA, however, came in Dublin. On 25 May 1921, several hundred IRA men from the Dublin Brigade occupied and burned the Custom House (the centre of local government in Ireland) in Dublin city centre. Symbolically, this was intended to show that British rule in Ireland was untenable. However, from a military point of view, it was a heavy defeat in which five IRA men were killed and over eighty captured. This showed the IRA was not well enough equipped or trained to take on British forces in a conventional manner. However, it did not, as is sometimes claimed, cripple the IRA in Dublin. The Dublin Brigade carried out 107 attacks in the city in May and 93 in June, showing a falloff in activity, but not a dramatic one. However, by July 1921, most IRA units were chronically short of both weapons and ammunition, with over 3,000 prisoners interned. Also, for all their effectiveness at guerrilla warfare, they had, as Richard Mulcahy recalled, "as yet not been able to drive the enemy out of anything but a fairly good sized police barracks".