So what went wrong here? Christiansen probably couldn’t remember the theory and put his rook on e1 instead of e2. Then he defended the f2-pawn with the bishop and this bishop with g3. Then he didn’t know what to do, so he put his king on a1. At that point the game was already over. What he completely missed was the critical point of the game, his one and only chance to turn the tide.
Play it safe!