Do a Goggle Search, 19th South Carolina, you will find the Commanding Officer at Kennasaw was Lt. Col. T. P. Shaw.

6/15-7/1-64 Kennasaw Mt. Atlanta Campaign Lt. Col. T.P. Shaw Manigault’s Brigade Brown's Divison Hood's Corps/II Corps

As to your question on entrenchments, I suggest you contact the Historian at the Kennesaw Mountain Battlefield Park, NPS. You can find him through the NPS website.

I remember trench lines when I lived in the area 20+ years ago and I became a member of the Kennesaw Mountain Battlefield Camp #700. SCV. This Park Historian at the time was a fellow named Kelly.

Also, a member of that camp was a descendant of Adm Semmes.

George Martin
Sparks, NV