Along with fellow British Army Generals Clinton and Burgoyne, Howe arrived there aboard on 25 May 1775, having learned en route that war had broken out with the skirmishes at the marches to Lexington and Concord in April. The "Cerberus" provided naval reinforcement at the Battle of Bunker Hill. He led a force of 4,000 troops sent to reinforce the 5,000 troops under General Thomas Gage who were besieged in the city after those battles. Gage, Howe, and Generals Clinton and Burgoyne discussed plans to break the siege. They formulated a plan to seize high ground around Boston and attack the besieging colonial militia forces, setting its execution for 18 June. However, the colonists learned of the plan and fortified the heights of Breed's Hill and nearby Bunker Hill on the Charlestown peninsula across the Charles River from Boston on the night of 16–17 June, forcing the British leadership to rethink their strategy.