While engaged in these activities Sherman conceived the idea that it might be more advantageous to by-pass Fort Pulaski and make a direct attack on the city of Savannah. He tried to sell this plan to the commander of the naval forces on whom he would have to depend for transport, protection, and assistance in the siege operations he had in mind. Du Pont obligingly ordered a reconnaissance of the winding waterways that led into the Savannah River above Fort Pulaski, but when he discovered how shallow these waterways were at certain stages of the tide, he pronounced the whole scheme impractical and dangerous. This difference of opinion between the Army and Navy commanders on the conduct of the campaign finally led to the removal of Sherman, but in the meantime the general ordered a tight noose of batteries and gunboats to be thrown around Fort Pulaski. When the Confederate supply ship, _Ida_, came down the Savannah River on the morning of February 13 on one of her regular trips to the fort, a battery of heavy guns, which the Federals had secretly constructed at Venus Point on the north bank of the river, opened up. The old sidewheeler ran the gauntlet under full steam with shots splashing in her wake. Luck was with her, for the Federal guns, after firing nine shots, recoiled off their platforms. It was the _Ida’s_ last trip to Pulaski. Two days later she slipped her moorings, ran down the South Channel under the guns of the fort, rounded the point at Lazaretto, and returned to Savannah through Tybee Creek and the Wilmington Narrows. During the following week the Federals completed the absolute investment or blockade of Fort Pulaski. They built another strong battery on the south bank of the Savannah River opposite Venus Point and threw a boom across Tybee Creek. To seal this waterway they entrenched two companies of infantry along its bank and assigned a gunboat to patrol the channel. At the same time they destroyed the telegraph line between Savannah and Cockspur Island. From now on neither supplies nor reinforcements could be brought to the fort, nor could the Confederate garrison escape to the mainland. After February 15 the only communication with Savannah was by courier who came and went by night through the marshes, often having to swim the creeks and rivers to avoid the Federal pickets. Five companies formed the garrison of Fort Pulaski when the fort was cut off. Company B of the Oglethorpe Light Infantry, the German Volunteers, the Washington Volunteers, and the Montgomery Guards were members of the 1st Regiment of Georgia Volunteers. The Macon Wise Guards was accredited to the 25th Regiment of Georgia Regulars. The total strength of the garrison was 385 officers and men. In command was Charles H. Olmstead, who had been elected colonel of the 1st Volunteer Regiment on December 26. To defend the fort there were 48 guns. [Illustration: _Col. Charles H. Olmstead, who defended Fort Pulaski._ Courtesy Miss Florence Olmstead.]