In the immediate aftermath of the Easter uprising the British authorities, taken by surprise, responded cautiously, uncertain of the forces and armaments arrayed against them. Martial law was declared on 25 April, and Brigadier General William Lowe arrived from Curragh barracks to take command of British operations. The approaches to Dublin Castle were secured, and its garrison reinforced, while the gunboat Helga was moored on the Liffey, and heavy artillery installed in Tara Street bombarded Liberty Hall, thought (mistakenly) to be the rebel HQ. Meanwhile, reinforcements were arriving in large numbers, and field artillery stationed at Trinity College began to pound the city centre. Troops converging on the city from Curragh barracks were blocked by a group of Irish Volunteers under Seán Heuston in the Mendicity Institution. While the rebels guarding the bridges across the Liffey sustained fierce assaults, the central garrisons at the Post Office and Four Courts were, as yet, unthreatened.
— OR —