On Lee's transfer to Richmond, he detailed urgent defense construction, then he called on Lawton's "earnest and close attention" to the Federal's probable approach to the city. "It looks now as if he would take the Savannah River". Guns located in island batteries were to be removed to the mainland in and around Savannah's defensive lines. Obstructions in the river above the city were to be set by hands provided by upriver planters in the event of an envelopment by way of Fort McAllister. "Every effort must be made" to retard or prevent further progress of the enemy directly upriver on the Savannah River approaches. "If he attempts to advance by batteries on the marshes or islands, he must be driven back, if possible." Scouts were ordered out "so as to discover his first lodgment, when they can be broken up." An additional three-gun battery at MacKay's Point was not intended to stop federal gunboats in force, but with Tattnall's gunboat support, they could prevent Federal batteries from being built on Elba Island to threaten Old Fort Jackson.