Positively identified numbers of African Americans at the Battle of Plymouth
This is not to say that there weren't others, but these are the men identified by name.
African Americans in white regiments (Cooks, etc.) – 11 total. 6 captured. 2 escaped. 1 MIA. 1 killed “while escaping” and another who refused to surrender and was killed.
Sailors – 9 total from the USS Southfield that are not accounted for. Listed as “Missing after Battle of Plymouth, NC.” No proof or reports that they were involved in a massacre. It is certainly possible some of these men drowned when the Southfield sank.
10th USCT – 19 enlisted men total. 6 captured and survived the battle. 7 escapes. 1 killed in battle. 1 killed possibly killed while escaping. 1 possibly killed after surrender. 3 unaccounted for. These 19 men were assigned to recruiting duty at Plymouth 26 March 64, less than a month before the battle. It is doubtful they had time to enlist many others, if any, into their regiment. One deposition states there were 35 Privates at Plymouth, but I have not been able to confirm that number.
2nd USCC – 5 enlisted men total. 2 captured. 2 escaped. 1 killed. 11 possible others who enlisted 1 March 64 at Plymouth, but weren't mustered until 29 June 64 at Bermuda Hundred, VA. They more than likely escaped during the battle.
37th USCT – 16 enlisted men total. 1 captured. 2 killed. 13 confirmed escapes. An additional 20 unnamed recruits show up at New Bern after the battle. Capt. Marvin states in Pvt. John Ward's pension file that there were about 40 men in the 37th USCT at Plymouth. He states that most of them were killed in battle. He states about 15 survived. No mention in the affidavit of any being murdered or massacred.
All told, my estimate is around a total of around 75 USCT who participated in the battle on April 20th. "Massacre at Plymouth" agrees with that number on page 180. There was also possibly an unknown number of African American government contractors and civilians who could have possibly been involved.
White USCT Officers - All identified themselves as being in other regiments and not captured as USCT except possibly Lieut. Parmenter, 10th USCT and Lieut Bascombe, 38th USCT.