Although Williams's battalion was ordered in August 1814 to be 'disposed for Naval service' and dispersed among the flotillas at Lake Ontario and Lake Champlain, the war did not finish for him. There was a third Royal Marine battalion which had arrived in July, and Williams – having seniority among the Marine field officers – became its new commanding officer. He was present in the Chesapeake campaign, participating in the Battle of Bladensburg, the attack on Washington, and the Battle of Baltimore. The men of his original battalion were redeployed, along with his new unit, to Tangier Island, on the understanding they would be spending the winter on the island.