The French acquired a copy of the British war plans, including the activities of Shirley and Johnson. Shirley's efforts to fortify Oswego were bogged down in logistical difficulties, exacerbated by Shirley's inexperience in managing large expeditions. In conjunction, Shirley was made aware that the French were massing for an attack on Fort Oswego in his absence when he planned to attack Fort Niagara. As a response, Shirley left garrisons at Oswego, Fort Bull, and Fort Williams (the latter two located on the Oneida Carry between the Mohawk River and Wood Creek at present-day Rome, New York). Supplies for use in the projected attack on Niagara were cached at Fort Bull.