Colonel Henry Knox took over command from the elderly Gridley on 17 November 1775. He immediately began the task of hauling the noble train of artillery from captured Fort Ticonderoga to Cambridge. This assignment was completed by the end of January. On 1 January 1776 the Rhode Island Train of Artillery merged with the Continental Artillery Regiment to form 12 companies altogether. There were two Rhode Island companies, those of Captains Ebenezer Stevens and Jotham Drury. The Fortification of Dorchester Heights in March 1776, in which Knox's artillery regiment was a critical component, hastened the end of the Siege of Boston.