Wofford was the original Colonel of the 18th GA and Solon Z Ruff was the original Lieut. Colonel. Joseph Armstrong was original Captain of I/18thGA. Wofford was absent at Fredericksburg and the regiment was commanded by 26 yo Lt Col Solon Z Ruff. Capt. Armstrong was wounded slightly at Fredericksburg. Soon after, Wofford was promoted to Brigadier; Ruff commanded the 18th GA at Gettysburg. Unfortunately, Ruff was killed in the failed assault on Fort Sanders at Knoxville (Nov 29, 1863) and Joseph Armstrong was elected Colonel. Somewhat ironically, Capt. Armstrong was spared from the failed assault on Fort Sanders by diarrhea. He was sent to Georgia and admitted at Ocmulgee Hospital Macon, GA on November 28, 1863. The assault happened the next day.
But I digress.

To your question: Armstrong was reported present with his regiment March 23, 1865 "near Richmond." On April 2 the Confederate line collapsed and Kershaw's division, including Wofford's old brigade (then commanded by Dudley DuBose) and the 18th GA, fell back through Richmond and crossed Mayo bridge. I assume Armstrong was still with them? Making their way south on April 6, they were stopped short at Sailor's Creek. Most of what remained of Wofford's brigade and Kershaw's division were captured at Sailors Creek. About 100 of the 18th GA were captured there.
IIRC only 1 officer and 52 enlisted men of the 18th Georgia escaped capture at Sailors Creek and made it to Appomattox. All of Kershaw's Division - of which the 18th Georgia was a part - was surrendered at Appomattox under Captains and Lieutenants. Lt. Gideon Ignatius Lasseter, commanding the 18th GA, was the highest ranking officer of the regiment present (except Capt. Espy of C.) Wofford's old brigade (what was left of the 16th, 18th, and 24th Georgia, Cobb's Legion, Phillip's Legion and the 3d Battalion Ga Sharpshooters) was surrendered under the command of Captain John Ferdinand Espy of Co C 18th GA.
In his incredibly well-written and deeply researched regimental history,
Stubborn Men and Parched Corn, Brig Gen McAbee states (on page 312 and again on page 496) that Armstrong was captured at Sailor's Creek. He cites this to Armstrong's obituary published in
Confederate Veteran and family genealogy. However, carded records show Armstrong surrendered at Petersburg on April 15, 1865 and was paroled from there. Another card says he was a Paroled Prisoner "Remaining in Richmond" on April 13, 1865 "On Parole until 10 am April 14, 1865." That's pretty specific. If he was paroled in Richmond until 10am April 14, I have no idea why he was moved to Petersburg and paroled again?
Here are a few possibilities.
1. He remained in Richmond when Kershaw's division passed through and was captured there and paroled April 13? Moved to Petersburg and paroled again? (Recall he was marked present on March 23)
2. He was with the regiment April 2 when Richmond fell and beyond, but became separated before Sailors Creek, was captured and returned to Richmond.
3. He was with the 18th at Sailors Creek and was captured there as McAbee states -- but was somehow sent to Richmond and Petersburg instead of Newport News -- like all the other prisoners.
4. He was with them at Sailors Creek and somehow escaped capture? Or was captured and escaped? And instead of going towards Appomattox, he went to Richmond? Where he was captured, paroled, and sent to Petersburg.
5. There may be other possibilities - but if McAbee says he was captured at Sailor's Creek, I'm guessing he actually was. McAbee is usually spot on.
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