2down, 6 letters, In 1794 in France getting beheaded was a mistake
I have E - R - - . Guessing it must be ERROR, but can't see why.
12 across, 4 letters, Miss US soldier on both sides. I have G - - -, so guess it might be GIRL but can only understand the GI half. Is RL a US soldier too?
The Terror was a period when they'd lop off your head as soon as look at you. Remove the head of 'terror' and you've error.
12a Seen this answered as 'Gigi