Looking through the list of officers in Bourland's Regt (very complete) I see no officer named Robbins, Van Robbins, or anything remotely similar. Likewise, in the list of all members of the regiment, no Robbins or similar name exists. There are 4 men with names starting with Ro. 1 Roberts, 2 Robertsons, and 1 Robinson. None were officers and none show that they were killed.

Unless your man was in another unit your mystery continues.

You could look up the individual records for every officer and see if any were killed on the right date, just in case the story is right, but the name is wrong.

Alan Whitehead