The Union advance on Fort Pulaski began on November 24, 1861. Following reconnaissance that Confederates had abandoned Tybee Island, Flag Officer Du Pont ordered forward an amphibious raid with three gunboats at the Tybee Island Lighthouse. Under a two-hour ship's bombardment, the Confederate pickets set fire to the lighthouse and withdrew. Commander Christopher Rodgers, USS "Flag", led a landing party of sailors and Marines in thirteen surf-boats to occupy the Lighthouse and the Martello tower, and flew the national flag from them. Overnight, a reduced company set false campfires to misdirect the Confederates ashore. Two days later commanding Flag Officer Du Pont and General Thomas Sherman made a personal reconnaissance, and on 29 November, General Gillmore, the command's chief engineering officer, with three companies of the Fourth New Hampshire, took formal possession of the entire island without opposition. The Navy set the logistics train in motion, and by December 20, the Army had sufficient materials for establishing "a permanent possession".