The only time I've had with variants of the Martin name is sometimes I'm asked if it's spelled ...ten. I've never investigated other spellings.

The American Civil War Research Database, Historical Data Systems, Inc., in their index of soldiers, displays a table which has a column “Events” in which they display a ‘P’ for POW if applicable.

Here are those I found listed as captured at Gettysburg. No telling how complete this is. However, it’s a start.

John Martin
"B" Co. GA 38th Infantry POW 7/4/1863 Gettysburg, PA
"H" Co. NC 26th Infantry John B. POW 7/2/1863 Gettysburg, PA
"H" Co. VA 18th Infantry John C. POW 7/3/1863 Gettysburg, PA
"G" Co. VA 57th Infantry John C. POW 7/3/1863 Gettysburg, PA
"D" Co. NC 32nd Infantry John E POW 7/3/1863 Gettysburg, PA
"L" Co. NC 21st Infantry John T., POW 7/3/1863 Gettysburg, PA

Thomas P. Martin none

No T. or T. P. Martin’s listed as POWs

Thomas Martin
"1st" Co. VA Rockbridge 1st Light Artillery POW 7/5/1863 Gettysburg, PA

"I" Co. AL 15th Infantry POW 7/2/1863 Gettysburg, PA