"ad hominem" is when a personal attack is used in place of a factual refutal.
He claimed that there was a wall extending along the East/West German border.
I provided photographic evidence that such was NOT the case.
He then tried to imply that the fault was mine because I did not accept his usage of "wall" to mean "fence with guard towers".
#1. There was no wall where he said there was one.
#2. Anyone who had been where he said he was, when he said he was there would have known that there was no wall there.
#3. Since anyone there, during that time, would have known that there was no wall there, that means that:
a. He wasn't there.
b. He can't tell a wall from a fence.
#4. Since he claimed he was there, and #2, then, he is not telling the truth.
#5. Someone who does not tell the truth is a (fill in the blank).
No. This wasn't an "ad hominem" attack.
This was defining his character based upon his behaviour in this discussion.
Cart before the horse.
His statement.
My factual refutation.
His semantic games.
My conclusion about his character.