 Lord Wimborne, the Lord Lieutenant, declared martial law on Tuesday evening and handed over civil power to Brigadier-General William Lowe.British forces initially put their efforts into securing the approaches to Dublin Castle and isolating the rebel headquarters, which they believed was in Liberty Hall.The British commander, Lowe, worked slowly, unsure of the size of the force he was up against, and with only 1,269 troops in the city when he arrived from the Curragh Camp in the early hours of Tuesday 25 April.