This letter from Lieutenant James W. Grace describing the combined action appears in [OAF] pp.39-40:

To: Brigadier General R.A. Pierce, Readville
July 22

Knowing your deep interest in the officers and men of the Regiment, I thought I would let you know how we are after our Skirmish and retreat from James Island and Fight at Morris Island.

We were on the move three days and nights before the Fight on this Island. When we arrived here, we were very much exhausted, tired and hungry, not having any thing to eat for twenty four, hours. I simply speak of this to let you know what condition we were in before the Fight. We arrived on the Island about 3 o’clock, rested a short time, and then moved forward to the upper end of the Island (the Island is about four miles long). When we arrived within one thousand yards of Fort Wagner, we laid down waiting for our support to come up. We laid there about thirty minutes when we were ordered to rise up and charge on the works, which we did at double quick time with a tremendous scream. When we arrived within a short distance of the works, the Rebels opened on us with grape and canister accompanied with a thousand muskets, mowing our men down by the hundreds. This caused us to fall back a little, but we soon made another rush to the works, when we received another tremendous discharge of musketry, and also grape and canister. Such a tremendous fire right in our faces caused us to fall back,  which we did in very good order. Our men are highly spoken of by military men as showing great bravery. They did fight when they were in front of the works [and a] good many of our men went on to the works and fought hand to hand with the Enemy.

Lieutenant James W. Grace