The Wayside Home appears to be a facility for rest and recuperation. See http://www.archive.org/stream/appealinbehalfof00sold#page/n1/mode/2up

The context is that Colquitt’s Brigade had been ordered to Virginia for the defense of Richmond. Butler and Burnside were threatening Petersburg to the south and Meade, with Grant calling the shots, was pushing through the Wilderness and Spotsylvania to the north. In response, Charleston, S.C. was stripped of defenders, first Hagood’s brigade, then Wise’s and Colquitt’s. Those detachments with temporary assignments like provost duty in Charleston or as part of the garrison at Fort Sumter were left behind to complete their duties and catch up when they could. The 19th Georgia started the trip north and got as far as Florence, S.C. before being ordered to return to Sullivan’s Island, where the regiment stayed for 3 days before departing again for Virginia and arrived in Petersburg on the 13th of May. The next day they were engaged at Drewry’s Bluff.

If you go back to page 485 of your reference you can see that on the 15th of May there were still 54 members of the 19th Georgia at Fort Sumter (under Capt. Keely). Since the commander at Fort Sumter on May 20th wanted Capt. Keely’s company (actually a detachment drawn from various companies) back from the Wayside Home, it seems likely that they had been relieved between the 15th and 20th and were at the Wayside Home awaiting transportation to Virginia. Capt. Mitchel’s request was apparently not granted, however, because Capt. Keely rejoined the regiment in the breastworks at Drewry’s Bluff a few days after the battle.

George