Commandant Ceannt decided that the South Dublin Union should have three outposts and assigned three captains, each with about twenty men, to the designated positions. Jameson’s Distillery in Marrowbone Lane a few hundred yards to the south east of the South Dublin Union was allocated to Captain Séamus Murphy. Capt. Thomas McCarthy took over Roe’s Distillery in Mount Brown and Captain Con Colbert and his company occupied Watkins’ brewery in Ardee Street to the east of the South Dublin Union.

By Tuesday evening it was clear that neither Watkins’ nor Roe’s had much strategic significance. As a result, Captain Colbert took his company to join Captain Séamus Murphy in Jameson’s Distillery. Captain McCarthy abandoned Roe’s and some members of the company joined the garrison at Jameson’s. The original number of twenty-one had expanded considerably with the addition of the two companies from the other outposts, members of Cumann na mBan, and men who were late in arriving.

The Jameson’s garrison had sight of certain positions within the South Dublin Union and made some small contribution to the action. It also incommoded military traffic to some extent, but played little part in determining the outcome of the Rising.