zumsel,
Unless we see different battle, I cannot find the damaged on Round 1, I cannot find anything wrong as per your report.
here are some rounds:
Round 1

Round 2

Round 6 (3 units down)

Round 7 (starting with 12 - 3 = 9 units)

Round 12 (last 6th unit down)

Results (6 units left)
